CINCINNATI -- Joey Votto gave the Washington Nationals one more heartache in a week already full of them.
Votto hit a grand slam in the ninth inning for his third home run of the game on Sunday, rallying the Cincinnati Reds to a rain-delayed 9-6 victory that knocked the Nationals out of first place in the NL East.
Washington headed home after a week that included two more players going on the disabled list with significant injuries and a 19-year-old rookie figuring in games in unusual ways.
Nothing was more unusual than how they let their chance to complete a sweep slip away.
"It was a tough night in the conditions and everything, but we gave them some cheap runs and you can't do that," manager Davey Johnson said.
They couldn't contain Votto, either.
The 2010 NL MVP hit solo homers in his first two at-bats off Edwin Jackson, then flied out to the warning track and doubled. Given one more chance by struggling closer Henry Rodriguez, he thrilled a crowd that sat through a long delay and then more rain.
Washington came into the game with only 15 homers allowed all season, fewest in the majors. Votto hadn't hit a homer since April 30.
He got the chance for last-swing drama when Rodriguez (1-3) got into the game and couldn't get comfortable on the wet mound. Rodriguez walked two batters with two outs to load the bases, including Chris Heisey after getting ahead in the count 0-2.
Johnson came out to visit Rodriguez, who repeatedly scraped at the wet mound with his cleats.
"Rodriguez didn't have command and he was kicking at the mound," Johnson said. "Rodriguez has done such a great job. You just can't walk guys like that. You don't want Votto up there ever. He walked the guys he should have gotten out."
Rodriguez left a 2-2 pitch up and over the plate for Votto, who hit it over the wall in center. He finished with a career-high six RBIs and the second three-homer game of his career.
The Reds said it was the first time in major league history that a player hit a game-ending grand slam for his third home run, according to research by the Elias Sports Bureau.
It was Votto's best day since he signed a new deal before opening day that added 10 years and $225 million.
"He did today what he's been known to do," Jackson said. "That's what he got paid a lot of money to do."
The last player to hit a game-ending home run in a three-homer game was Albert Pujols for St. Louis against Cincinnati on April 16, 2006, according to STATS LLC.
Giancarlo Stanton also hit a game-ending slam Sunday for Miami against the New York Mets, making it the first time in 14 years that there were two walk-off slams on one day, STATS said. Mo Vaughn connected for Boston and Steve Finley for San Diego on April 10, 1998.
A few thousand fans were left to cheer Cincinnati's first game-ending grand slam since Adam Dunn connected off Cleveland's Bob Wickman on June 30, 2006.
Sean Marshall (1-2) got the win at the end of the long day. The start was delayed 3 hours, 36 minutes by rain, which continued to fall throughout the 3-hour, 45-minute game.
Ahead 6-3, the Nationals couldn't close out what would have been their first three-game sweep of the season. The Reds got two runs in the eighth when rookie right fielder Bryce Harper lost Jay Bruce's two-out fly ball in the twilight sky, letting it fall way behind him for a double.
"Once the ball got above the stands, I lost it," Harper said. "It was hazy. I had no clue. I didn't think he hit it that deep."
Then, their closer let it slip away, concluding a painful one-week trip.
Right fielder Jayson Werth had surgery on his broken left wrist Monday, and Harper needed 10 stitches for a self-inflicted gash above his left eye on Friday after he hurt himself slamming a bat against a wall near the dugout. Catcher Wilson Ramos tore the anterior cruciate ligament in his right knee while chasing a passed ball Saturday night.
Despite sending 11 players to the disabled list already this season, the Nationals had managed to stay atop the NL East because of their pitching staff, which leads the majors. For one of the few times, it let them down, and Washington dropped into second place behind Atlanta.
NOTES: The Nationals headed out for a seven-game homestand, including two games each against San Diego and Pittsburgh and three against Baltimore. The Reds left for an unusual seven-game trip: Atlanta for two games, then on to New York for two against the Mets and three against the Yankees. ... The Nationals called up C Sandy Leon from Double-A Harrisburg. ... Harper wore a bandage over his left eye for the second straight game and had a pair of singles, ending his 0-for-9 slump in Cincinnati. ... Reds 3B Mike Costanzo, called up to replace injured Scott Rolen, made his big league debut as a pinch-hitter in the fifth and hit a sacrifice fly on the first pitch.