OAKLAND, Calif. -- Evan Gattis hit two home runs, right-hander Collin McHugh won his fifth straight game and the Houston Astros continued their wild-card playoff push with a 6-5 victory against the Oakland Athletics on Wednesday afternoon.

The Astros, who entered the game trailing Baltimore by two games for the American League's second wild-card spot, beat the A's for the seventh straight time and completed their second straight three-game series sweep of Oakland.

McHugh (12-10) allowed two runs on six hits over 5 2/3 innings, striking out five and walking two. He won his 11th straight September game in 13 starts since 2014 with the Astros and improved to 6-1 for his career against Oakland.

Gattis hit his team- and career-high 29th and 30th home runs. He launched a two-run shot during a three-run rally in the sixth inning. Then in the eighth, he led off with a monstrous blast to center field, increasing Houston's lead to 6-4. Gattis set a career high with 27 homers last season, his first with Houston.

Carlos Correa went 2-for-4 with an RBI double and scored a run. Jose Altuve had two hits in five at-bats and scored a run.

A's rookie right-hander Daniel Mengden (2-9) retired the first 10 hitters he faced but allowed four runs on six hits over 5 2/3 innings and left the game with Oakland trailing 4-1. Mengden, who struck out seven and walked two, fell to 0-7 at the Coliseum in eight starts. In his previous start at Kansas City, he pitched seven shutout innings in a 14-5 victory, his first win since June 27 at San Francisco.

The A's took a 1-0 lead in the fourth inning. Danny Valencia led off with a walk, moved to second on Marcus Semien's single and scored on Brett Eibner's ground-rule double that one-hopped over the wall in right field.

Houston pulled even with a run in the fifth. Marwin Gonzalez worked a leadoff walk and moved to second with one out when Mengden walked Jason Castro. Both runners advanced on a wild pitch, and Gonzalez scored on Jake Marisnick's ground out.

The Astros scored three more times in the sixth, taking a 4-1 lead and knocking Mengden out of the game.

Altuve lined a single to left with one out and scored on Correa's double to right center that landed on the warning track. Gattis followed with a two-run shot, sending Mengden's 1-2 curveball over the left field fence.

Tony Kemp tripled down the right field line later in the sixth, ending Mengden's outing.

Oakland cut the Astros lead to 4-2 in the sixth when Valencia led off with an infield single and scored on rookie Bruce Maxwell's double to right-center.

Houston answered with a run in the seventh. George Springer led off with a double, moved to third on a wild pitch and scored on Yuli Gurriel's ground out to Semien. Springer took off for home the instant Semien threw to first and barely beat Yonder Alonso's throw home with a head-first slide, touching the plate with his left hand.

The A's cut Houston's lead to 5-4 with two runs in the bottom of the seventh. Jake Smolinski led off with a walk and moved to third on pinch-hitter Chadd Pinder's double to center off lefty Tony Sipp. Stephen Vogt brought Smolinski home with a ground out, and Pinder scored on Ryon Healy's ground out.

Gattis sent Zach Neal's first-pitch fastball in the eighth high and deep over the center-field fence, giving him his second two-homer game of the season.

The A's scored an unearned run in the ninth off Luke Gregerson, but he recovered to earn his 15th save. Pinder walked with two outs and scored when Vogt's ground ball got past Altuve for an error. Pinch runner Arismendy Alcantara was caught stealing by Castro for the third out.

NOTES: Oakland LF Khris Davis, who has 40 home runs and 99 RBIs, was out of the lineup for the second straight game because of an illness. ... Astros OF Colby Rasmus missed his third straight game and remained day-to-day because of what manager A.J. Hinch described as "a lot of different" physical problems. "He's less than 100 percent and he doesn't feel good enough," Hinch said. ... Astros OF Preston Tucker was scheduled to undergo right shoulder surgery Wednesday in Houston. "It will be a few months before he picks up a bat or swings a bat," Hinch said. "We expect him to be ready for spring training." ... A's RHP J.B. Wendelken will get a second opinion to determine whether he'll need to undergo Tommy John surgery, manager Bob Melvin said. "The ligament is compromised," Melvin said. "I guess you would have to say there's a chance, unfortunately." ... A's RHP Sonny Gray will pitch a simulated game Saturday. If all goes well, that could be the last step before Gray pitches in a game. He has been on the disabled list since Aug. 7.