Gonzalez has won three straight and six of his past seven starts, pitching to a 2.89 earned run average and recording 40 strikeouts in that span. He has only given up four runs over his current three-game win streak, tossing 7 1/3 frames of one-run ball to beat the Angels on Friday.
The victory pushed the 26-year-old's record to 15-12 with a 3.25 earned run average. He also won a personal-best 15 games last year.
"I did my best to keep us in the game. I was extremely focused and wanted to pound the strike zone," said Gonzalez after his last win.
Gonzalez is 5-2 with a 3.68 ERA lifetime versus the Mariners, who counter with rookie Anthony Vasquez.
The 25-year-old will make the seventh start of his career and has dropped five in a row since winning his MLB debut on Aug. 23 in Cleveland. Vasquez has given up at least five runs in four of his six games, including back-to-back losses to Texas.
Vasquez, a lefty, yielded 10 runs, 14 hits and six homers over 6 1/3 innings of the two starts, giving him a season ERA of 8.89. He faces the A's for the first time.
A series victory is on the line tonight after Oakland rebounded from Monday's loss to claim a 7-0 victory last night. Trevor Cahill tossed seven scoreless innings, scattering four hits and only walking one while striking out seven.
"I think that's the guy we're used to seeing," A's manager Bob Melvin said of Cahill. "He was working his pitches on both sides of the plate, backdoor sinkers in the middle, he's got a lot of weapons and you saw all of them tonight."
Blake Beavan was roughed up in five innings. The righty gave up seven runs on eight hits while fanning two and walking four.
"Blake was a little bit out of sync early on, a little choppy," Mariners manager Eric Wedge said. "We wanted to give him time to work his way out of trouble early. He didn't have the fastball command we're used to seeing him have."
The A's swept a three-game set at home when these clubs last met, but the Mariners still lead the season series, 10-8.