OAKLAND, Calif. (AP) -- On Jason Giambi T-shirt day, the Oakland Athletics slugger put on a show.

Giambi hit his fifth career grand slam and Tim Hudson pitched seven scoreless innings Sunday as the A's broke out of an offensive drought with an 13-4 victory over the Minnesota Twins.

"It's definitely a great feeling and it's nice thing to have in front of all the kids and the big crowd," said Giambi, the subject of the promotion that helped draw 34,065 to the Oakland Coliseum, the second-largest crowd of the year.

"But we just needed to get a win today and get back on track. It was nice to get some momentum now that we're going on the road."

The A's stopped their season-high five-game losing streak and prevented Minnesota's first four-game sweep in Oakland since 1993.

Hudson (5-2), who decided the team should wear its black jerseys on a sweltering day in keeping with the black T-shirts being given away, allowed four hits while striking six and walking four. He won his fourth straight decision.

"I felt like it was a good idea for us to wear black and go hand in hand with the fans," Hudson said. "It was going to be smoking regardless of what jersey we wore and we were getting beat up pretty good with the whites, so we tried something different."

Ryan Christenson had an inside-the-park homer in the eighth for Oakland and Eric Chavez hit a solo shot. Ben Grieve had four hits and Ramon Hernandez had three.

Oakland had been struggling offensively, managing a season-low three hits in three of their previous four games. The A's were batting just .131 in that span and had failed to score in 14 straight innings.

It all changed in the second, when the A's sent 12 batters to the plate and matched their season-high for runs in an inning, highlighted by Giambi's towering drive to center that bounced off the cement facade just below the second-deck suites.

"You've got to have guys on to drive them in and guys like Terrence Long and Randy Velarde are getting on base all the time," Giambi said. "It's put me in position where I've been able to hit with guys in scoring position. I'm just being selective out there and hitting the ball hard."

The homer was the AL-leading 17th for Giambi, one behind St. Louis' Mark McGwire for the major league lead. He also leads the league with 51 RBI.

"The game obviously got away from us in the second," Minnesota manager Tom Kelly said. "That was just too big of an inning to overcome."

Sean Bergman (2-3) failed to get out of the second, allowing eight runs on six hits in 1 1/3 innings. He hasn't won since April 25 and two of his three losses in that span have been to the A's, who have gotten to him for 13 earned runs in 4 1/3 innings.

"I pitched poorly," Bergman said. "I gave the team absolutely no chance to win the game. It was 8-0 real quick.

"But of all the pitches, there's only one I'd take back -- the one to Giambi. I thought I'd made decent pitches before that. But that pitch was kind of a backbreaker."

In the second, Grieve singled and Matt Stairs, after third baseman Corey Koskie lost his foul popup in the sun, singled sharply to center. Bergman walked Jeremy Giambi to load the bases and Miguel Tejada followed with a two-run single.

Chavez walked to reload the bases and Hernandez and Terrence Long each singled to drive in a run, putting Oakland up 4-0. Bergman fanned Randy Velarde for the first out of the inning but Giambi then worked the count to 3-1 before connecting for the slam and chasing Bergman.

Minnesota didn't score until the eighth, when Cristian Guzman homered off reliever Doug Jones as part of a four-run burst.

Christenson's homer came on a line drive that rolled into the right-field corner past Brian Buchanan. The rookie couldn't get the ball back to the infield before Christenson rounded the bases.

Game notes
Giambi's slam was the fifth by the A's this season, tying St. Louis for most in the majors. It was also the second of the year by Giambi, who also hit a slam April 9 against the Chicago White Sox. ... Minnesota's Denny Hocking was scratched from the lineup prior to the game because of a strained left hip flexor. He had tormented the A's, going 9-for-13 with four RBI in three previous games. ... Christenson's inside-the-park homer was the first in Oakland since Terry Steinbach did it Sept. 26, 1996.