BOSTON -- It took Jason Varitek nearly eight seasons to hit his first grand slam. His second one came a lot sooner.
Varitek hit a two-out 0-2 fastball from Kris Benson (4-3) into the Baltimore bullpen in right field to give the Red Sox a 4-1 first-inning lead. It was the second career grand slam for Varitek and first of the season for the Red Sox, who improved to 6-0 against Baltimore this season and have won four straight overall.
"I was actually looking out over the plate, and I just happened to actually react to it," said Varitek, whose first grand slam came in August. "I was able to get on top of it."
That was all the run support left-hander Lenny DiNardo needed to earn his first career victory. DiNardo, making his fourth start of the season and fifth of his career, pitched five sharp innings, allowing two runs -- one earned -- and two hits. He struck out five and walked five.
"I didn't think about it until after the game," DiNardo said. "I was just sitting on the couch looking through game notes, and I thought, 'Very cool.' Each start, I feel like I get something from it. This one in particular was a confidence builder."
After getting two quick outs to start the game, DiNardo walked four consecutive batters to force in a run. But Kevin Millar struck out swinging with the bases loaded to end the first, and DiNardo settled down from there.
"It was not a good start," Baltimore manager Sam Perlozzo said. "It seems like we just can't seem to take advantage of some situations lately."
DiNardo (1-1) needed just seven pitches to retire the side in the second inning. He got Millar to ground into a double play to strand two runners in the third and allowed just one hit total in the fourth and fifth innings before being relieved by Julian Tavarez.
"We haven't gotten the big hits when we needed to," said Millar, who stranded six runners. "I'm as much to blame as anyone right now."
Benson allowed nine runs and eight hits in 4 1/3 innings for Baltimore, which ended its road trip 0-5 and has lost 12 of 15 games.
Melvin Mora scored on DiNardo's throwing error in the third to pull Baltimore within two but the Red Sox scored five runs in the fifth.
Trot Nixon and Mike Lowell each had two-run doubles in the inning. Lowell's bases-loaded double with one out chased Benson from the game. Wily Mo Pena then drove in a run with a sacrifice fly to extend Boston's lead to 9-2.
"We swung the bats pretty well," Lowell said. "I think we're playing a complete game of baseball right now. Our defense is playing well, our pitchers our doing well, we're swinging the bats. If we do that, I think it's a good recipe to win."
Mark Loretta and Kevin Youkilis had three hits and Manny Ramirez went 2-for-2 for the Red Sox.
Jeff Conine went 1-for-2 with an RBI for the Orioles.
Left-hander David Wells and right-handed reliever David Riske threw bullpen sessions for Boston prior to the game. Wells is scheduled to throw another bullpen session Wednesday, while Riske is slated to pitch an inning for Triple-A Pawtucket on Wednesday. ... DiNardo's error in the third inning was Boston's only error in its six-game homestand. ... DiNardo became the first left-handed pitcher to record a win for the Red Sox this season. ... It was the shortest outing of the season for Benson. ... The Orioles fell to 1-9 in games started by left-handed pitchers. ... Baltimore hosts Boston on May 15 in the next matchup between the two teams.