NEW HAVEN, Conn. — Top-seeded Sara Errani fell to Russia's Ekaterina Makarova 7-5, 6-1 on Wednesday at the New Haven Open.
Errani, ranked No. 5 in the world, became the fifth of the tournament's eight seeds to lose in the first two rounds of the final WTA tuneup before next week's U.S. Open.
"The good thing is that if you lose, you have more time to prepare there, if not, you have more confidence," Errani said. "I hope the court there will be different."
Fourth-seeded Caroline Wozniacki became the first seeded player to make it to the quarterfinals, beating Karin Knapp 6-1, 7-5. Defending champion Petra Kvitova joined her with a tough three-set win over American qualifier Alison Riske 7-6 (5), 4-6, 6-3. And American Sloane Stephens, the sixth seed, also advanced in three sets, 7-5, 2-6, 6-1 over Julia Goerges of Germany.
After being dominated in the second set, Stephens won the next four games and cruised to the win.
"I think me being able to go out and play a third set strong like that is the difference between me today and a year ago," Stephens said. "I just think that I'm at a point where I go out there and I'm like, `I'm going to win.'"
Stephens, who is ranked 17th in the world, is still looking for her first tournament title. She will play the marquee match in the quarterfinals against Wozniacki, who has won this event in four of the last five years.
The former No. 1 player in the world cruised through her first set with Knapp, then fought through some health issues to hold on for the win. Wozniacki, who has been battling a cold this week, called for a trainer after experiencing some dizziness in the 90-degree temperatures while up 3-2 in the second set. The Danish star dropped the next two games before rallying.
"I'm definitely feeling much better," she said after the match. "I was feeling worse in the beginning of the week."
Kvitova found herself in a back-and-forth match with the 23-year-old Riske, before breaking her at love in the fifth game of the final set.
"After dropping the second set, it was quite tough to come back in the third. But I'm glad for it, I'm sure," she said.
Errani didn't make it through her first match of the tournament, after receiving a bye in the first round. She had trouble with her slow, spinning serves all afternoon on what she said was a faster-than expected court. She was broken four times by Makarova.
The 25-year-old Russian dominated her own service games, was broken just once and had eight aces.
"Today was a good day for me and all my shots was working really good," Makarova said. "I understood a little bit more how to play against her."
Makarova will play Simona Halep in the quarterfinals.
Halep didn't have a WTA title before this year, but has three this summer and is 28-5 in her last 33 matches. She dropped her first set Wednesday but bounced back for a 3-6, 6-4, 6-1 win over Carla Suarez Navarro of Spain.
The 21-year-old Romanian also attributed her slow start to the 90-degree heat, which she said caused to alter her game plan in the second set.
"I played more offensive, more aggressive and I just tried to finish the point very fast," she said.