BOSTON –– Jacoby Ellsbury stole home to help lead the Red Sox to a series-sweeping win against the New York Yankees on Sunday at Fenway. With Justin Masterson giving the Sox 5.1 strong innings, the Boston beat New York, 4-1

The win gives the Red Sox a 10-game win streak going into Monday’s series against Cleveland.

Masterson came into the game knowing that he needed a quality start to take the pressure off a beleaguered bullpen that had been exhausted in the last two Yankee-Red Sox games. His 5.1 one-run innings wasn’t a complete game, but from the converted reliever, it was enough.

"I just got some fly balls when we needed them, got some ground balls when we needed them, and was able to get through and then have a solid bullpen outing," Masterson said.

Yankee lefty Andy Pettitte threw four good innings to match Masterson, but was undone in the fifth. He walked Jason Varitek and Jacoby Ellsbury before allowing a double to David Ortiz, scoring Varitek to make it a 2-1 game. With first base open, the Yankees intentionally walked righty Kevin Youkilis, bringing up left-handed J.D. Drew with Ellsbury on third.

As Pettitte delivered his 1-1 pitch, Ellsbury took off for home, accomplishing the first Red Sox straight steal of home plate in 15 years.

"The biggest thing is, I got the courage to go, I guess. In that situation, bases loaded, you’ve got to make it. It could be one of hte worst baserunning mistakes if you don’t make it, but I was pretty confident that i could get in there and make it -- so that’s why I went," Ellsbury said.

With the crowd still going wild and the game now 3-1, Drew golfed a ground-rule double into the right field stands, scoring Ortiz for a 4-1 lead.

Both early runs came via sacrifice flies. The Yankees’ Brett Gardner hit one to left to score Hideki Matsui in the top of the third, and David Ortiz lofted a sacrifice to left to score Jacoby Ellsbury in the bottom of the inning.

For a team that was having trouble scoring runs before this winning streak, seeing offense of all types, from home runs to steals of home, has been satisfying.

"We’ve swung the bats a lot better than we did at the start. Our bullpen’s been our strength, and it’s allowed our offense to settle in," said captain Jason Varitek.

Masterson threw 99 pitches, allowing one run on six hits and one walk, and striking out four. He was relieved by Hunter Jones, who threw two-thirds of a scoreless inning.

Converted starter Michael Bowden came on after Jones and threw two perfect innings, striking out Derek Jeter and Robinson Cano. Bowden had been called up early Sunday morning to take the pressure off the bullpen, and he came through, despite some jitters.

“I think I was a little passive at first -- I just wanted to throw strikes and get ahead, which I didn’t do at all -- I think I had to throw two balls to every guy. Then I got focused, and then started throwing strikes,” Bowden said.

With Jonathan Papelbon unavailable after pitching two straight nights, Takashi Saito got the save for Boston.

The win capped off a 10-game win streak for Boston, bringing the team from 2-6 to 12-6, and only 1 game out of first place. Francona said he’ll take it, but staying on an even keel is what brought them out of the cellar in the first place, and they’ll stay even so as not to fall back in.

"I would rather win than lose, but I don’t want to get too carried away with what happened this homestand, because when we’re 2-6 the big thing we talk about is staying in the moment. I think that’s the best way to have success, to not think about last week. It was a good homestand for us –– that’s stating the obvious. And much needed."

The Yankees, meanwhile, limp home now two games behind Boston, and 3 out of first.

"You don’t want to lose in your division. You don’t want to lose to anyone in your division, you don’t want to get swept. After two tough losses, this was a much crisper game. We weren’t able to get anything offensively, but there’s a long, long way to go. We have to turn it around tomorrow," Girardi said.

Drew left the game after the seventh inning with what Francona said was a tight left quad muscle. He will not play Monday against Cleveland, and Jeff Bailey is likely to take his place.

dbarbari@projo.com