The Athletics came from behind twice to cool off the Rays, who slipped 3 1/2 games behind the New York Yankees in the American League East. Oakland won for the seventh time in nine games.
A run-scoring double in the seventh by Derek Norris lifted Oakland into a 3-3 tie and the A's moved in front in the eighth against reliever Joel Peralta.
After Peralta (1-6) had retired the first two batters in the inning, Chris Carter reached on a single. Gomes then hit the first pitch he saw over the wall in left.
Grant Balfour gave up a run with nobody out in the ninth, but retired the next three batters to pick up his 13th save and preserve the win for Ryan Cook (1-0).
Cook struck out four and did not allow a hit in 1 2/3 innings of relief.