The 39-year-old right-hander earned his 17th win, and the Yankees got home runs from Alex Rodriguez and Xavier Nady in a 7-2 victory over the Tampa Bay Rays on Tuesday night that included a scoreless relief outing by Joba Chamberlain.
"We're just trying to win ballgames any way we can. I'm trying to contribute on my day," Mussina said. "We battled to get out of some situations. We got some big hits we needed."
Chamberlain came off the disabled list for New York and pitched 1 1/3 scoreless innings. Tampa Bay's lead in the AL East was trimmed to four games over Boston, which beat Baltimore 14-2.
Mussina (17-7) got his 267th win, passing Hall of Famers Bob Feller and Eppa Rixey for sole possession of 34th place on the career list. One thing that's eluded him, though, is a 20-win season.
"Obviously, you would like to see a guy that has been so good for so long be able to achieve that," Yankees manager Joe Girardi said. "It's kind of neat that he's chasing it."
Mussina allowed two runs and 10 hits in six-plus innings. He matched a season high with eight strikeouts, improving to 3-0 against the Rays. He also beat them on April 7 and May 14, and his 19 career wins tie him with Tim Wakefield for the most by any pitcher against Tampa Bay.
Nady hit a two-run homer off Matt Garza (11-8) for the third-place Yankees, who have won 10 of 16.
Rodriguez hit home run No. 548, tying Hall of Famer Mike Schmidt for 12th on the career list. The eighth-inning solo shot off Jason Hammel was his 30th of the year, giving A-Rod 11 consecutive seasons -- and 12 overall -- with 30 or more.
Meanwhile, Chamberlain made a strong return from a month stay on the DL. He entered with runners on first and third with two outs in the seventh inning and needed just one pitch to get out of the jam.
"It felt good," Chamberlain said. "My mechanics were kind of off, all over the place. But at the end of the day, there's a zero. That's what a month does physically. I came out great."
The right-hander was placed on the DL with right rotator cuff tendinitis on Aug. 6, two days after he left a start against Texas with shoulder soreness. The Yankees expect him to work out of the bullpen the rest of the season.
Chamberlain allowed one hit and walked one in 1 1/3 innings. Dan Giese, also activated from the DL on Tuesday, worked the ninth in a non-save situation.
"Joba looked good for not being out there for a while," Girardi said.
Mussina, 19-7 lifetime against Tampa Bay, gave up an RBI single to Cliff Floyd in the third and left after Gabe Gross and Shawn Riggans opened the seventh with consecutive doubles to trim New York's lead to 6-2.
Akinori Iwamura followed with a single, putting runners at the corners with no outs, but the Yankees' bullpen didn't allow any more damage.
Damaso Marte struck out B.J. Upton and Carlos Pena. Chamberlain entered to a standing ovation from Yankees fans among the crowd of 21,629 and got pinch-hitter Rocco Baldelli to ground into a force play on a 96 mph fastball.
The Rays, who had won five in a row, are beginning a stretch of 19 consecutive games against clubs in playoff contention, including six against Boston and five more against the Yankees -- one of just two AL teams with winning records against Tampa Bay this season.
"I know they've hit a few tough moments this year. But they are the Yankees. They are very talented and they beat us again," Rays manager Joe Maddon said. "We'll put it behind us and play them again."
Johnny Damon, Jason Giambi and Hideki Matsui all drove in one run apiece against Garza, who yielded six runs and five hits in five-plus innings. The right-hander had allowed four runs combined in his previous three starts.
The Yankees are 8-5 against Tampa Bay. Cleveland is the other AL team with a winning record (5-2) against the AL East leaders. ... Rays closer Troy Percival, out since Aug. 14 because of cartilage damage in his right knee, was reinstated from the disabled list. C John Jaso (Triple-A Durham) and RHP Juan Salas (Double-A Montgomery) were recalled from the minors. ... Yankees general manager Brian Cashman, in the final year of his contract, met with team co-chairmen Hank and Hal Steinbrenner at the club's complex in Tampa. He said an extension was not discussed.