TORONTO -- Jon Jones successfully defended his light heavyweight title, surviving an early scare to submit former champion Vitor Belfort in the fourth round at UFC 152 on Saturday night.

Belfort came close with an armbar in the first round, but Jones' reach, varied attack and ground and pound took a toll on the veteran challenger.

Unable to get his striking game going, Belfort tried to take the fight to the ground where he could use his jiu-jitsu. But he paid a price and finally fell victim to an Americana submission 54 seconds into the round. Jones improved to 17-1, and Belfort dropped to 21-10.

In the co-main event at the Air Canada Centre, Demetrious Johnson won a split decision – 48-47, 47-48, 49-46 – over Joseph Benavidez to become the UFC's first flyweight champion.

Jones took down Belfort down 30 seconds after the opening bell, and the Brazilian responded with an armbar attempt that looked dangerous. Jones slammed Belfort down to the canvas and eventually wriggled free as the crowd began to chant "Vitor! Vitor!"

"I've never had my arm pop like that before," said Jones, who said he would have let his arm break rather than tap out.

Jones remained on top and began to throw elbows, cutting Belfort. The doctor had a look at the battered challenger between rounds.

Belfort, who does his best work traditionally in the first round, came out punching in the second. But he had a hard time penetrating Jones' reach. The champion began to pick away at Belfort, who pulled guard later in the round to bring the fight back to the ground.

Belfort took some more elbows as he tried to get into position for another submission attempt.

Jones put him down with a kick to the rib in the third. This time, Jones let him get back up only to have Belfort pull guard again.

"Go with your punches if you want to win this fight," Belfort's cornerman yelled between rounds.

He did but pulled guard again and Jones went to work with some elbows before cranking Belfort's arm back and forcing the tapout.

"That's why he's a champion," said Belfort, who said he had hurt his rib in training.

Jones arrived at the post-fight news conference with his right arm in a sling. He said there was no prognosis yet but that he may have sustained nerve damage.

Johnson (16-2-1) beat Benavidez (16-3) in the battle of the little men – Johnson is 5-foot-3 and Benavidez 5-4. Benavidez looked to press, but the faster Johnson simply wore him down. He had a cut on his left eye in the third round, as well as redness on his legs from Johnson kicks.

Benavidez did get Johnson down in the fourth round, but failed to take advantage. He tried for a choke and ended up having to fight off a leg lock. Johnson opened the fifth with a pair of quick takedowns.

Both fighters raised their hands in victory after the fight, but Johnson did it faster and with more conviction.

"I was a little shocked," Johnson said about the split decision. "I've still got to prove a lot of things."

Featherweight Cub Swanson had one of the night's highlights, an eye-popping KO over highly touted Charles Oliveira thanks to a clubbing right to the temple of the American-based Brazilian.

Oliveira (16-3 with one no contest) stood still for several seconds and then toppled, prompting referee Yves Lavigne to step in at 2:40 of the first round. Oliveira left the cage with the support of a cornerman.

Swanson (18-5) had hurt him with a shot to the liver seconds before.

English middleweight Michael Bisping showed his all-around game in winning unanimously 29-28 over Brian Stann. Bisping improved to 24-4, and Stann fell to 12-5.

The card was UFC's 10th show in Canada and third in Toronto.

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  • Jon Jones; Vitor Belfort

    Jon Jones waits for the fight to start against Vitor Belfort during the light heavyweight championship title bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Jon Jones; Vitor Belfort

    Jon Jones, top, chokes Vitor Belfort during the light heavyweight championship title bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Jon Jones; Vitor Belfort

    Jon Jones, right, kicks Vitor Belfort in the face during the light heavyweight championship title bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/Nathan Denette, The Canadian Press)

  • Jon Jones; Vitor Belfort

    Jon Jones, top, drops Vitor Belfort on his head during the light heavyweight championship title bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Jon Jones; Vitor Belfort

    Jon Jones, left, punches Vitor Belfort during the light heavyweight championship title bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Joseph Benavidez; Demetrious Johnson

    Joseph Benavidez, left, throws punch on Demetrious Johnson during the flyweight championship title bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Joseph Benavidez; Demetrious Johnson

    Demetrious Johnson holds the winning belt after defeating Joseph Benavidez during the flyweight championship title bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Joseph Benavidez; Demetrious Johnson

    Joseph Benavidez, left, throws punch on Demetrious Johnson during the flyweight championship title bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Jon Jones; Vitor Belfort

    Jon Jones, top, drops Vitor Belfort on his head during the light heavyweight championship title bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Jon Jones; Vitor Belfort

    Jon Jones, top, chokes Vitor Belfort during the light heavyweight championship title bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/Nathan Denette, The Canadian Press)

  • Michael Bisping; Brian Stann

    Michael Bisping, left, battles against Brian Stann during the middleweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Joseph Benavidez; Demetrious Johnson

    Joseph Benavidez, right, throws punch on Demetrious Johnson during the flyweight championship title bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Joseph Benavidez; Demetrious Johnson

    Joseph Benavidez, right, battles against Demetrious Johnson during the flyweight championship title bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Joseph Benavidez; Demetrious Johnson

    Demetrious Johnson holds the winning belt after defeating Joseph Benavidez during the flyweight championship title bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Roger Hollett; Matt Hamill

    Roger Hollett, left, of Canada, gets taken down by Matt Hamill during the light heavyweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Michael Bisping, Brian Stann

    Michael Bisping, right, delivers punch to the face of Brian Stann during a middleweight bout at UFC 152 in Toronto, Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Michael Bisping; Brian Stann

    Michael Bisping, right, delivers punch to the face of Brian Stann during the middleweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Cub Swanson; Charles Oliveira

    Cub Swanson, left, battles against Charles Oliveira during the featherweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Cub Swanson; Charles Oliveira

    Cub Swanson, right, throws the knock out punch to Charles Oliveira during the featherweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Cub Swanson; Charles Oliveira

    Cub Swanson, left, battles against Charles Oliveira during the featherweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Cub Swanson; Charles Oliveira

    Cub Swanson reacts after knocking out Charles Oliveira during the featherweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Igor Pokrajac; Vinny Magalhaes

    Igor Pokrajac, left, battles with Vinny Magalhaes during the light heavyweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Roger Hollett; Matt Hamill

    Roger Hollett, right, of Canada, throws a punch against Matt Hamill during the light heavyweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Roger Hollett; Matt Hamill

    Roger Hollett, right, of Canada, throws a punch against Matt Hamill during the light heavyweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Mitch Gagnon

    Mitch Gagnon, of Canada, reacts after defeating Walel Watson during the bantamweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • TJ Grant; Evan Dunham

    TJ Grant, left, of Canada, fights Evan Dunham during the middleweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Igor Pokrajac; Vinny Magalhaes

    Vinny Magalhaes reacts after defeating Igor Pokrajac during the light heavyweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • TJ Grant; Evan Dunham

    TJ Grant, left, of Canada, fights Evan Dunham during the middleweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Igor Pokrajac; Vinny Magalhaes

    Igor Pokrajac, right, battles with Vinny Magalhaes during the light heavyweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Sean Pearson; Lance Benoist

    Canada's Sean Pearson, right, fights Lance Benoist during the light heavyweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Sean Pearson; Lance Benoist

    Canada's Sean Pearson, right, fights Lance Benoist during the light heavyweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Sean Pearson; Lance Benoist

    Canadian Sean Pearson, top, takes down Lance Benoist during the light heavyweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Jimy Hettes; Marcus Brimage

    Marcus Brimage, left, punches Jimy Hettes during the welterweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Jimy Hettes; Marcus Brimage

    Marcus Brimage, left, punches Jimy Hettes during the welterweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Jimy Hettes; Marcus Brimage

    Marcus Brimage, left, punches Jimy Hettes during the welterweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Seth Baczynski; Simeon Thoresen

    Seth Baczynski, left, fights Simeon Thoresen during the featherweight bout of their UFC 152 match in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Seth Baczynski; Simeon Thoresen

    Seth Baczynski, right, fights Simeon Thoresen during the featherweight bout of their UFC 152 match in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Jimy Hettes; Marcus Brimage

    Marcus Brimage, front, gets choked by Jimy Hettes during the welterweight bout at UFC 152 in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Jimy Hettes; Marcus Brimage

    Marcus Brimage, left, punches Jimy Hettes during the welterweight bout of their UFC 152 match in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Seth Baczynski

    Seth Baczynski reacts after knocking out Simeon Thoresen during the featherweight bout of their UFC 152 match in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Mitch Gagnon

    Mitch Gagnon, of Canada, reacts after defeating Walel Watson during the bantamweight bout of their UFC 152 match in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Mitch Gagnon; Walel Watson

    Mitch Gagnon, left, of Canada, takes down Walel Watson during the bantamweight bout of their UFC 152 match in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)

  • Mitch Gagnon; Walel Watson

    Mitch Gagnon, left, of Canada, takes down Walel Watson during the bantamweight bout of their UFC 152 match in Toronto on Saturday, Sept. 22, 2012. (AP Photo/The Canadian Press, Nathan Denette)