NEW YORK -- Mike Mussina was baffling batters with dipping curveballs and a fastball that topped 90 mph.
Back on the mound for the first time in more than three weeks after recovering from elbow trouble, he gave the New York Yankees the type of pitching performance that could push them over the top in their quest for an eighth straight AL East title.
Mussina threw six impressive innings, Jorge Posada supplied a tying home run in the fifth inning and a three-run, upper-deck drive in the sixth and the Yankees survived another meltdown by their middle relievers to beat the Baltimore Orioles 7-6 on Thursday night.
"I had to find out, and we had to find out whether I could go out there and pitch," said Mussina, who had been sidelined since Aug. 29 because of elbow inflammation. "You can't throw a test out there the last week of the year or in the postseason, when every game is as big as they are. I had to know now whether I could go do it or whether I couldn't."
His answer sounded like The Little Engine That Could.
"I think that I can," he said.
A night after moving past the Boston Red Sox to take over first place in the AL East for the first time since July 18, the Yankees won for the 10th time in 11 games -- seven of the wins by one run -- and opened a season-high one-game lead with 10 remaining. Mussina is on track to pitch the season finale Oct. 2 at Fenway Park.
"It's huge," Yankees captain Derek Jeter said. "Hopefully he's healthy tomorrow and he can continue to go for us."
Mussina (13-8) allowed four hits in six innings, struck out six and walked none, throwing 58 of 76 pitches for strikes -- and starting 19 of 24 batters with a strike. Baltimore's only run off him came in the third, and it was unearned.
Luis Matos singled leading off, Jeter allowed David Newhan's potential double-play grounder to bounce past him at shortstop for an error, and Bernie Castro singled in the run. With two on and no outs, Mussina retired Melvin Mora on a soft liner to Jeter.
Al Leiter pitched a 1-2-3 seventh, then gave up run-scoring hits to Tejada and Gibbons in the eighth. Tanyon Sturtze allowed an RBI grounder to B.J. Surhoff and a run-scoring double to Javy Lopez - runs that were charged to Leiter.
Gary Sheffield also homered for the Yankees, reaching 30 for the third straight season and eighth time overall.
Posada has tried to inspire the Yankees for the stretch run, handing out T-shirts to teammates that say "Grind It" on the front and "There is no trying, there is only doing or not doing" on the back.
He led by example as New York completed a four-game sweep of the Orioles, who at 70-82 are assured their eighth straight losing season, the worst stretch for the franchise since the St. Louis Browns/Orioles went 11 in a row from 1946-56.
"I think we're doing everything we can," Orioles interim manager Sam Perlozzo said. "I just wish we were winning. I don't like it at all."
Bruce Chen (12-10) retired 12 straight batters before Posada led off the fifth with a drive just to the left of straightway center, tying the score 1-1.
Then in the sixth, Tejada allowed Cano's hard one-hopper to shortstop bounce off him for an error. Sheffield's single moved Cano to second, and Cano slid home ahead of Jay Gibbons' throw on Hideki Matsui's single to right for a 2-1 lead.
Posada followed with a drive about five rows into the left-field upper deck that finished Chen.
"I'm seeing a lot of good results," said Posada, batting .351 in September with four homers and 15 RBI.
Chen, who had allowed two earned runs or fewer in eight of his previous nine starts, gave up five runs -- four earned -- and five hits in 5 1/3 innings. Pitching coach Ray Miller had told him to throw breaking balls to Posada, but Chen gave up both homers on fastballs.
"His pitch selection I thought got a little off," Perlozzo said.
Cano tripled off Aaron Rakers leading off the seventh, a drive about 6 inches from the top of the right-field wall, and scored on Alex Rodriguez's sacrifice fly. Sheffield's second homer in three games made it 7-1.
"We haven't accomplished anything yet," Yankees manager Joe Torre said, "other than playing tough games every night, which I'm not sure is going to be good for my health."
- The Yankees will start RHP Chien-Ming Wang on Sunday and send RHP Aaron Small (9-0) to the bullpen.
- Gibbons went to first base in the fourth, when Mussina bounced a 2-2 pitch that appeared to hit him on the foot. Gibbons went to first, but plate umpire Randy Marsh ruled he swung and struck out.
- Posada had his second multihomer game this season and the 11th of his career. He has 19 home runs this season.