The Oakland A's came from behind on consecutive home runs by Mike Heath and the red-hot Mike Davis in the fourth inning last night and made Seattle a loser, 7-4, for the first time this season. It was the Mariners' first venture outside their Kingdome.

Heath's homer, his first, was an inside-the-park drive and tied the game at 3 off Mark Langston (1-1). Davis then put Oakland ahead with his third homer, giving him 11 RBI in the last four games and 13 for the week-old season.

Heath, the A's leadoff hitter in the fourth, hit a drive to right-center and the ball bounced off the Oakland Coliseum fence and rolled about 30 feet from center fielder Dave Henderson. Heath's headfirst slide home beat the relay throw by inches.

Davis' game-winner, over the right field fence, came on a 2-2 pitch from Langston.

Bill Krueger (1-1) won with six innings of work. Jay Howell got the last four outs for his second save.

Dave Kingman drove in an Oakland run with a double in the first inning and another with a single off reliever Mike Stanton in the seventh.

After Al Cowens' homer brought the Mariners within a run, Oakland made it 7-4 in the eighth with a run-scoring single by Dave Collins and a sacrifice fly by Carney Lansford.