Nick Markakis knocked in the other run for the Orioles, who swept the series and have won five of their last six.

"When you beat good teams, it does a little bit for your confidence," Payton said about the series win over the defending champions. "We feel like we can compete with anybody. We go out there like everybody else thinking we can win the ball game."

Orioles starter Daniel Cabrera (4-1) went seven innings and allowed three runs on 10 hits with three strikeouts and no walks to record his second straight win. George Sherrill pitched a scoreless ninth for his 15th save.

Jason Varitek and Mike Lowell homered while Jacoby Ellsbury had three hits and scored a run for the Red Sox, who failed to protect a three-run lead for the second consecutive game and lost for the fourth straight time.

Sox reliever Craig Hansen (0-2) took the loss, charged with two runs while not recording an out. Starter Jon Lester was solid, giving up five hits and two runs over six frames.

Baltimore went on top for good in the seventh inning.

Javier Lopez retired the first two batters before allowing an infield single to Freddie Bynum. Hansen came on and allowed a base hit to Guillermo Quiroz and a walk to Brian Roberts before exiting the game.

Hideki Okajima was called upon, but left a pitch down and in to Payton, who connected on a line-shot grand slam to left field which gave the O's a 6-3 edge.

"That's the first time that a team's brought a lefty in to get me out, but I had made three outs earlier against a lefty," said Payton. "I was just looking for something out over the plate. Fortunately, he gave me a split finger that was over the plate and I was able to hit it hard."

Matt Albers pitched a scoreless eighth and Sherrill closed out the Red Sox in the ninth despite allowing singles to Lowell and Varitek.

Boston picked up a run in the first, as Ellsbury led off with a single, stole second and scored on a Dustin Pedroia base hit.

Manny Ramirez robbed the O's of at least one run in the fourth, making a running catch just in front of the wall in left on a ball hit by Kevin Millar, then throwing to first in time to double off Aubrey Huff.

Varitek launched his first of the season, to the seats in right-center with one out, to make it 2-0 for the Sox in the fifth.

Lowell followed with a two-out solo homer to left in the sixth, but Baltimore got to Lester for two runs in the home half on a Payton groundout and a Markakis single.

Game Notes

Prior to the game, the Sox placed pitcher Clay Buchholz on the 15-day disabled list Wednesday with a broken nail on his right hand. To take Buchholz's spot on the roster, the Red Sox recalled outfielder Jonathan Van Every from Triple- A Pawtucket. He went 1-for-3 in his major-league debut...Baltimore begins interleague play by hosting Washington starting Friday...Boston finished its 10-game road trip a disappointing 4-6, and returns home Friday to open up a three-game interleague series against Milwaukee.