Kurt Suzuki and Mark Ellis had RBI hits in a three-run fourth inning against A.J. Burnett (10-6) in the Yankees' second straight loss on this West Coast trip.
Three relievers finished the shutout, the fourth this season against the Yankees, who lead the majors in home runs and are second to the Los Angeles Angels in runs scored.
Tomko (2-2) knows well how powerful the Yankees can be, having spent more than two months with the team earlier this season. But it comes as a bit of a surprise that he managed to silence his former teammates' bats.
The only real threat he faced came in the third inning when the Yankees loaded the bases with one out. But Tomko induced Alex Rodriguez to hit a comebacker and started a 1-2-3 double play.
Tomko allowed five hits and one walk before leaving after 78 pitches in his first start since May 26, 2008, for Kansas City. Tomko started the season in the Yankees' organization and was called up to the majors in May. He went 1-2 with a 5.23 ERA in 15 relief appearances before being designated for assignment on July 21.
The A's signed him to a minor league deal earlier this month and he made three appearances in the minors before getting the start against his former team.
Oakland gave Tomko all the support he needed in the fourth inning. Rajai Davis started the rally with a one-out double and then stole third, his 25th steal of the season. Suzuki's single knocked in the first run. With runners on second and third and two outs, Burnett stopped his delivery in the middle for a balk. Ellis' double knocked in the third run.
Tomko left an inning later in his longest major league outing since his last start.
Craig Breslow followed with two scoreless innings and Brad Zeigler struck out Jorge Posada with two runners on to end the eighth. Andrew Bailey pitched a perfect ninth for his 18th save, finishing Oakland's sixth shutout of the season.
NOTES: New York had homered in 14 straight games, matching its longest streak since a 16-gamer in 1994. … The day after breaking Luis Aparicio's all-time hits record for a shortstop, Derek Jeter started at DH for the Yankees. … Yankees OF Nick Swisher doubled in the seventh inning and has reached base safely in 26 straight games. … Athletics INF Bobby Crosby left the game with tightness in his left calf. … Tomko's start ended a streak of 15 straight games started by an Oakland rookie.