Mussina pitched seven strong innings, allowing five singles, and New York beat the slumping Chicago White Sox 3-1, sending the AL Central leaders to their season-worst sixth straight loss.
"Two tough games down in Tampa and it was good to come out and win this game," Mussina said after getting his team-best 12th victory.
New York is behind in both the AL East and wild-card races in a season that Mussina said has featured plenty of unexpected turns and twists. And there are still six weeks to go.
"This has been a strange year for a lot of reasons. We've had some big injuries and we were up and down very drastically the first half of the season," he said.
"We've had a lot of tough losses, a lot of tough stretches," he said.
Mussina (12-7) got stronger after escaping the first inning when the White Sox had three singles and scored their only run. He walked one and struck out seven while allowing four baserunners after the opening inning.
"I didn't think the first inning was that bad. They fisted a couple of balls into the outfield," Mussina said. "After that, I made some good pitches."
New York pushed across two runs in the fifth off Jon Garland,
who failed to become the American League's first 17-game winner.
Garland (16-7) gave up seven hits and three runs -- two earned -- and lost for the third time in his last four starts as Chicago continued its horrid play at home, where it has dropped 14 of 20.
"You can't worry about it," Garland said of the White Sox's anemic offense. "You worry about it and you get away from your game. ... We need to get back to the little things, get back to getting guys on, bunting them over and stealing. We'll be all right."
The White Sox got an unexpected blow before the game even started when home run and RBI leader Paul Konerko was scratched from the lineup after straining his back in batting practice on one of his final swings.
"It feels sore and a little weak," Konerko said, sounding like he might not play the rest of the series. "Nothing since I've ever played baseball have I taken one swing and halted activity after a swing. Ever. Unless a guy hit me with a pitch in the hand or the face or whatever."
New York broke a 1-1 tie in the fifth as Tino Martinez and Robinson Cano singled with one out. Martinez took third on the play and Cano advanced to second when White Sox right fielder Jermaine Dye fumbled the ball for an error.
But that was it for the White Sox because Mussina got better the longer he pitched.
"He's been a life saver for us, a leader of this ball club. He's been as consistent as they come," New York manager Joe Torre said.
New York tied it in the third when Cano, entering the game in a 2-for-19 slump and dropped to No. 9 in the order, singled, moved up on Jeter's sacrifice, went to third on a fly ball and scored on Gary Sheffield's single past third. Sheffield was caught off first on the play and tagged out.
It was Mussina's second win over Chicago this month. He allowed eight hits and two runs in six innings on Aug. 8, the Yankees' lone win in a three-game series in New York. ... The White Sox are also without leadoff hitter and major-league stolen base leader Scott Podsednik, who is on the disabled list with an adductor muscle injury. Podsednik said Friday the injury was getting better each day. He was put on the DL on Monday retroactive to Aug. 13. ... New York's Jason Giambi was 0-for-3 with a walk and is in an 0-for-18 skid. ... The announced crowd of 39,496 was the second largest of the season and represented the 14th sellout this year at U.S. Cellular Field. ... Dye was 1-for-22 when he singled in the sixth.