NEW YORK (AP) - Joba Chamberlain sauntered over to the media huddled around his locker, hesitating for just a moment before plunging into the middle of the cameras.

''I didn't even do anything today,'' he said under his breath.

He didn't have to, with the way the Yankees are swinging the bats.

Mike Mussina survived five shaky innings before turning it over to Chamberlain and New York's reshaped bullpen, and the Yankees pummeled the Seattle Mariners 12-6 on Saturday for their first four-game winning streak this season.

Jason Giambi hit a three-run homer and Bobby Abreu added a two-run shot for the Yankees, who have outscored Baltimore and Seattle 35-9 during the winning streak. Abreu finished with four RBIs, and Robinson Cano went 4-for-4 and matched a career-high with three doubles as the Yankees improved to 5-0 against the Mariners this season.

''It's exciting to kind of turn the corner and get some of these hits to fall,'' Giambi said. ''We were kind of finding ways to lose every night. Now we're playing good baseball.''

Things couldn't be much different for Seattle.

The Mariners have been outscored 44-12 by the Yankees and have lost 18 of 23 overall, dropping to a league-worst 18-32.

Plate umpire Larry Vanover tried to end Seattle's misery a strike early, signaling strike three on Adrian Beltre with two outs in the ninth.

The Yankees started to come off the field, and ''New York, New York'' started playing on the public-address system. Then Beltre pointed out to the umpire that it was only strike two. After Vanover checked with a crew mate, Beltre resumed his plate appearance and, five pitches later, he grounded out.

''We're not playing good baseball,'' said Seattle manager John McLaren, whose future is becoming increasingly uncertain. ''The important thing is not to make excuses. You have to fight through it. We're the only ones who can get us out of it.''

Coming off his worst start in more than a decade, Mussina (7-4) started on three days' rest and needed 74 pitches to make it through five innings. He wasted a 4-0 lead, giving up Jose Vidro 's three-run homer in the fourth followed by Beltre's solo shot.

Chamberlain entered in the sixth to a big ovation from the crowd of 53,512. Manager Joe Girardi wanted him to throw about 45 pitches in his second appearance since starting the transition from setup man to starter and, just as planned, the hard-throwing rookie struck out a pair in the sixth and got out of a jam in the seventh before Kyle Farnsworth relieved.

Chamberlain threw 40 pitches.

''I wanted to go back out there, but it's a process and you have to be patient,'' he said, sounding a bit exasperated. ''It's going to take forever, is what it feels like.''

The bumbling Mariners are on their third five-game skid of the season, and have been outscored 55-22 so far on this six-game trip through Detroit and New York, a pair of clubs that began the week last in their divisions.

Carlos Silva (3-4), also pitching on short rest, gave up seven runs - five earned - and 11 hits in six innings. He was 3-0 with a 2.79 ERA before a disastrous outing May 4 against the Yankees, and has seen his ERA climb to 5.14 with five poor starts this month.

Girardi was back on the Yankees bench after serving a one-game suspension for a theatrical tirade Thursday night in which he kicked his hat and inadvertently sent dirt on an umpire, leading to an ejection in the ninth inning. McLaren was tossed Friday night for arguing a called third strike against Ichiro Suzuki .

The Yankees got to Silva in the second inning, when Giambi connected on a 1-2 pitch for an opposite-field, three-run homer to left. Cano followed with a double - again to left-center - and two batters later Melky Cabrera made it 4-0 with a blooper to left.

Mussina had gone 16 starts without allowing a homer to a left-handed hitter before Vidro's drive.

Cabrera gave the Yankees the lead back in the third with an RBI single, and Abreu's two-run shot in the sixth - made possible when second baseman Jose Lopez booted Derek Jeter 's ground ball with two out - pushed the lead to 7-4. The Yankees added five more in the seventh, helped by three walks and an error on Beltre.

''I think we're OK now, ''Abreu said. ''That's the way we play. We're aggressive, score some runs - this is us.''

Notes: Playing around with his 6-year-old son Dante on the field afterward, Girardi took a wild throw to the side of his face. He walked off holding his cheek but hollered up to chuckling reporters that he was OK. ... The Mariners' Richie Sexson struck out three times before hitting a two-run homer in the eighth. He's struck out 49 times in 149 at-bats this year. ... Yankees INF Wilson Betemit (hamstring) planned to make another rehab start at Triple-A Scranton-Wilkes-Barre on Saturday and could rejoin the club Monday in Baltimore. ... C Kenji Johjima was back in the Seattle lineup after a day off.