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Clay Buchholz aims to keep his perfect record intact on Sunday when the Boston Red Sox try to complete a three-game sweep of the New York Yankees at Fenway Park.

Buchholz was the best pitcher in baseball through the first two-plus months of the season, racking up a 9-0 mark to go along with a stingy 1.71 ERA. But after giving up two runs in 6 2/3 innings in a win over the Los Angeles Angels of Anaheim on June 8, Buchholz was sidelined for more than three months with a right bursa sac strain.

The right-hander returned to a big league mound on Tuesday against Tampa Bay, and showed no signs of rust, as he scattered three hits and struck out six over five scoreless innings to improve to 10-0 and lower his overall ERA to an amazing 1.61.

"I had a lot of three-ball counts, and that's probably the worst thing I could say about it," Buchholz said. "I was able to miss the fat part of the bat and get some ground balls. Getting a couple of runners thrown out helps. It felt good.

"I just want to build up now and maybe after next time I won't have to worry about pitch counts. I just want to help this team in October. It's been fun to watch them even though it's been frustrating not to participate. I've had to be patient and now I'm able to get out there. I just want to do my part."

Buchholz, though, is just 4-5 lifetime against the Yankees with a 5.86 ERA in 11 starts.

New York, meanwhile, will rely on righty Ivan Nova, who has been the Yankees' best starter for the last month and a half, but is dealing with some tightness in his triceps. Nova did not get a decision in Baltimore on Tuesday, as he allowed four runs and six hits in six innings of his team's 7-5 win.

"He had this thing that he's dealt with for awhile now," Yankees manager Joe Girardi said. "It hasn't kept him from making a start. Sometimes it tightens up a little bit. He said it tightened up a little bit, so I took him out."

Nova is 4-0 over his last eight starts and is 8-4 on the year with a 3.17 ERA.

Boston continued to destroy New York's postseason hopes on Saturday, as Jon Lester outpitched CC Sabathia, throwing eight strong innings to guide the Red Sox to a 5-1 win.

Lester (14-8) allowed three hits and two walks with five strikeouts, extending his turnaround from a stretch of 11 starts between May 20 and July 13 when the lefty went 2-6 with a 6.27 ERA.

He is 6-2 in his last 11 starts and has trimmed his ERA from 4.58 to 3.75.

"I believe in myself, these guys believe in me and I knew going through what I went through in the middle of the year it was just a matter of time ... that things would take care of themselves," said Lester.

Sabathia (13-13) gave up nine hits, four walks and five runs with five strikeouts in six innings.

Shane Victorino and Jonny Gomes both had two hits and an RBI for the Red Sox, who took three of four from the Yanks last weekend and have won nine of their last 11 overall.

The Yankees, now 3-3 on a 10-game road trip and trying to stay in the AL wild card race, played without outfielder Alfonso Soriano, who was scratched from the lineup with a thumb injury he suffered earlier this week in Baltimore.

"It was bothering him yesterday but they said it was OK. Today it was worse. I'm not sure why," said Girardi. "It's hard to figure out."

Boston is 12-6 against the Yankees this season.