Olivares (10-9) allowed one run in six innings to win his second game since being traded to the A's on July 29, and Oakland beat Roger Clemens and the New York Yankees 6-1 Tuesday to stay close in the AL wild-card race.
"Right now I'm going out there and fighting for something, I'm playing for something," Olivares said. "It's different than playing for pride. The momentum is here and the idea that we can make it is here."
The A's improved their home record to a major league best 41-18 and stopped the Yankees' six-game winning streak.
"Olivares went out there and matched Clemens zero for zero through six innings and gave us a chance to stay in there," A's manager Art Howe said. "On days like today, we're a better team than them we outplayed them, outpitched them and outhit them."
Clemens (10-5) had allowed just four hits entering the sixth. But Randy Velarde led off with a single and Jason Giambi walked. With one out, Spiezio doubled over center fielder Bernie Williams. Fie pitches later, Grieve hit his 18th homer.
The loss broke a streak of 13 straight winning decisions in the month of August for Clemens, who allowed five runs, nine hits and five walks in 6 1-3 innings. He struck out four.
"In a game that's 0-0, you want to minimize your mistakes," Clemens said. "I got the ball up to Grieve, and they put up a crooked number."
The Yankees scored in the seventh on a double by Ricky Ledee, an infield single by Jim Leyritz and an RBI double by Jorge Posada that knocked out Olivares. But with runners on second and third, T.J. Mathews came in and got three straight outs.
"You come in the game with a couple of guys in scoring position against the Yankees, who are so explosive, and it's a bonus if you get out of it without a run scoring," Mathews said. "Against the Yankees, if you throw a zero up there it's definitely a confidence booster."
Doug Jones got four outs for his sixth save this season and 297th of his career, tying Jeff Montgomery for 10th place.
The low-scoring game came just a few hours after the Yankees defeated the A's 12-8 Monday night. Williams' grand slam capped an eight-run second inning for New York in the series opener.
The A's have not lost consecutive games at home since being swept in a four-game series by Cleveland from April 26-29.
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