HOUSTON -- With center fielder Sam Fuld producing another awesome catch, Danny Valencia delivering more jaw-dropping power, and right-handed revelation Ryan Dull continuing his season of excellence across three levels, the Athletics showed they aren't just playing out the string.

Valencia smacked two home runs, including a two-run blast in the eighth inning that delivered the Oakland Athletics a 4-3 comeback win over the reeling Houston Astros on Friday night at Minute Maid Park.

Valencia erased a 3-2 deficit with his one-out shot off Houston right-hander Pat Neshek (3-6) for his career-high 16th homer, continuing his tormenting of the Astros with his second career multi-homer game.

Valencia, selected off waivers from the Blue Jays on Aug. 3, went 3-for-3 with a walk, two runs and three RBIs and is batting .452 (14-for-31) with four homers and 11 RBIs against the Astros (77-71) this season.

"I was capitalizing on mistakes, just like any guy in our lineup would have done," Valencia said. "Fortunately for me, I got some hitter's counts. It just felt good that we won and that I came through for the team."

Left-hander Drew Pomeranz (5-5) worked a perfect seventh inning as the Athletics (64-84) held the Astros hitless over final five frames. Oakland left-hander Felix Doubront started that run by retiring the final seven batters he faced before departing after six solid innings of work, and Dull closed out the Astros by breezing through the eighth and ninth innings, allowing one walk with two strikeouts for his first career save.

Dull has worked 11 scoreless innings over his eight career outings.

"Pretty amazing for a guy that started in Double A," Athletics manager Bob Melvin said of Dull. "Ends up coming up here and when you look at the numbers and you see what he's done to this point (it's impressive).

"We've run him through the middle of the order with some of the better teams in the league, we've run him two innings like we did today. At the beginning of the year, we really didn't know much about Ryan Dull and now we're getting to know a lot about him."

The Astros dropped their fifth consecutive game following a 2-8 road trip. They remain 2 1/2 games behind the Texas Rangers in the American League West, who dropped a 3-1 decision to the Mariners.

For a spell, the Astros found the productive at-bats that deserted them on their discouraging road trip, manufacturing runs in the first and third innings to complement a solo home run from first baseman Chris Carter, his 19th, with one out in the second.

Second baseman Jose Altuve was the linchpin, working a leadoff walk in the first before advancing one base over the ensuing two plate appearances -- a George Springer sacrifice bunt and a groundout to the right side of the infield from shortstop Carlos Correa. The Astros led 1-0 when Altuve scored on an RBI single from third baseman Jed Lowrie.

In the third, Altuve scored again, this time on a daring tag from third base when Lowrie lifted a fly ball into right-field foul territory. Athletics right fielder Josh Reddick delivered a strong throw home, but Altuve beat the tag of catcher Carson Blair, taking out home plate umpire Toby Basner with his slide in the process to push the Houston lead to 3-0.

But Oakland mounted its comeback off Astros right-hander Mike Fiers, starting with back-to-back home runs in the fourth. Reddick bashed a 2-2 fastball off the facade of the right-field upper deck for his 19th homer before Valencia drilled a fastball 408 feet out to left.

"I really haven't found out what to do with Valencia yet," Fiers said. "Reddick got on top of the high fastball. Hats off to him, and Valencia just seems to swing well against me and against us as a team."

That uprising followed a spectacular diving catch in right-center by Fuld that robbed Correa of a base and potentially two RBIs with both Altuve and Springer on base and no outs in the bottom of the third.

"Sort of symbolizes how the week has gone," Astros manager A.J. Hinch said. "We've found a way, a lot of different ways to just miss or have a couple of tough losses. That's not how you draw it up. I think that game was ours to win and we didn't do enough to win which has been the way the week's gone."

NOTES: Astros INF Marwin Gonzalez remained sidelined as he continues to deal with multiple hand issues. Gonzalez missed two games during the road trip with a left index finger and left wrist injury before injuring his left thumb attempting to field a ground ball on Wednesday night. ... Athletics OF Billy Burns missed his eighth consecutive start with right hamstring soreness but pinch-hit in the seventh inning and is slated to return to the starting lineup on Saturday. ... Astros RHP Luke Gregerson is expected to rejoin the team on Saturday following the Wednesday birth of his first child, Logan John Gregerson, in Orlando, Fla. Gregerson last appeared on Sunday, earning his 27th save against the Angels.