OAKLAND, Calif. -- Oakland A's right-hander Sonny Gray continued to make his Cy Young Award case Friday night, throwing his fifth career complete game and outdueling Houston Astros lefty Dallas Keuchel in a battle of American League contenders for the award.

Gray (12-4) allowed just one run on five hits in a 3-1 victory at the O.co Coliseum. He struck out five and walked none, winning for the fifth time in his past six decisions. Gray lowered his ERA to 2.06.

"I haven't seen anyone better," A's catcher Josh Phegley said. "The stuff he's managed to do, with our record, and us losing a lot of games this year has been tough. He goes out there and puts together a performance every time he's on the mound, so he's right up there."

Keuchel (13-6) allowed three runs and 10 hits over 7 2/3 innings, striking out three and walking two. Not bad, by any means, but not good enough on this night against Gray.

"I'm not really pitching against the other pitcher, it's the other team and their lineup," Gray said. "That's really what my focus is going in.

"I just challenged them a lot with my fastball. It wasn't the best that it's been. Slider wasn't the best that it's been, but I was trying to make them put the ball in play as quick as possible and as early in counts as possible."

Keuchel had gone 1-0 with a 0.00 ERA in his first two starts against the A's this year.

"It was just one of those days where I'd like to have a few plays back," Keuchel said. "Botched about three balls that I usually make and that was the difference. Early on I felt well. Was making quality pitches in hitter's counts on the road against a quality opponent, even though they're not playing ball like they'd like to. I can't afford to do that and that cost me."

A's third baseman Danny Valencia went 2-for-3 with a solo home run leading off the third inning. It was his eighth blast of the season and first since being claimed off waivers by the A's from Toronto on Monday.

A's manager Bob Melvin took one look at Valencia's career numbers against Keuchel and decided to have him hit cleanup. Valencia entered the game batting .556 against Keuchel, going 5-for-9 with two doubles, one home run and three RBIs.

"He's very tough," Valencia said of Keuchel. "The numbers, a lot of that's luck sometimes. You get some pitches to hit and you capitalize on it."

Phegley went 2-for-4 with an RBI double and scored a run for the A's. He went the opposite way to right field on both his hits.

"Our approach was better," Melvin said. "You really have to stay the other way with him. With that sinker, if you try to pull him you're going to wear the shortstop and third baseman out all game long."

Astros first baseman Luis Valbuena hit his 21st home run of the season, a solo shot in the fifth inning.

The first-place Astros' lead in the AL West over the Angels fell to 1 1/2 games, thanks in large part to Gray.

"He was good and we expected him to be good," Astros manager A.J. Hinch said of Gray. "He's one of the best pitchers in the league. We had, counted, six or seven well-hit outs. Thought we put up good at-bats. We didn't get the results we wanted, but I can't argue too much with the quality of at-bats we put up."

The A's pushed across a run in the second inning to take a 1-0 lead, sending eight men to the plate and forcing Keuchel to throw 26 pitches, raising his total to 47.

Phegley lined a leadoff single to right and moved to second on shortstop Marcus Semien's single to center. First baseman Mark Canha loaded the bases with an infield single that ricocheted off a leaping Keuchel's glove. With one out, center fielder Billy Burns brought Phegley home with a sacrifice fly to right.

Valencia made it 2-0 in the third with a leadoff home run over the left-center-field wall.

Houston cut the Oakland lead to 2-1 in the top of the fifth when Valbuena sent Gray's 94 mph, 3-2 fastball into the right-field seats with two outs.

The A's answered with a run in the bottom of the fifth when Phegley hit a ground rule, RBI double to right.

NOTES: Astros LF Preston Tucker (right arm contusion) started Friday night after being out of the lineup for two games. ... Houston 2B Jose Altuve entered the game with an American League-best 30 steals. He is the fourth player in franchise history to have at least 30 steals in four consecutive seasons. Altuve did not have any steals Friday. ... A's RF Josh Reddick was out of the starting lineup Friday night against Houston and left-hander Dallas Keuchel. Reddick, a left-handed hitter, is 1-for-15 lifetime against Keuchel. He's also still nursing a sore lower back. He started Thursday for the first time since being injured Sunday against Cleveland, and A's manager Bob Melvin decided "this is a good day to give him a day off." ... The A's acquired minor-league RHP Dawrin Frias from the Mets on Friday as the player to be named in their Aug. 4 trade of LHP Eric O'Flaherty. Frias, 23, was assigned to Class A Vermont.