HOUSTON -- Astros right-hander Joe Musgrove, an unexpected revelation out of the bullpen, helped crystalize how much things can change during a six-month season.

Right-hander Collin McHugh worked six shutout innings before a reconfigured bullpen completed the Houston Astros' 3-0 victory over the Oakland Athletics on Saturday night at Minute Maid Park.

McHugh (1-2) earned his first victory on the season in his sixth start after missing three-plus months with an elbow injury. However, it was a bit of a rocky road for McHugh, who retired the side in order only once and relied on timely grounders and his defense to negate baserunners.

The Astros (76-47) turned three double plays behind McHugh, who allowed six hits and walked one batter while striking out three, and six overall. Oakland went 0-for-2 with runners in scoring position thanks in large part to baserunners being eliminated before reaching second.

"It just didn't roll our way today," Athletics catcher Bruce Maxwell said. "Slightly to the left or the right or maybe a little bit in the air and it's a different ballgame. But tonight, that was our kryptonite."

Athletics right-hander Kendall Graveman (3-4) matched McHugh by working six innings, allowing six hits and striking out three. But he surrendered a two-run single to Marwin Gonzalez in the fourth inning, a grounder that clipped the glove of lunging second baseman Jed Lowrie.

Astros third baseman Alex Bregman supplied an insurance tally in the eighth inning, his 15th home run of the season and second in as many games.

Francisco Liriano, Musgrove and Tyler Clippard, relative newcomers to the Houston bullpen, worked an inning apiece to close out the Astros' 12th victory in 14 games against Oakland (53-70) this season. Liriano and Clippard were acquired via trade over the last three weeks while Musgrove continued his excellent work since being bumped from the rotation in mid-June.

In nine relief appearances since June 22, Musgrove has allowed one run with 15 strikeouts over 14 1/3 innings. He induced a double play and struck out Marcus Semien in the eighth.

"Musgrove's really pitched his way to more interesting outings out of the bullpen," Astros manager A.J. Hinch said. "His velocity is up, his slider has gotten better. His energy on the mound is exceptional. There's a better vibe about him so it was a good test for him today with the two-run lead."

McHugh labored early and needed 24 pitches to complete the second inning. He snagged a fielder's choice grounder to erase Semien, who had doubled with one out in the first inning, and worked around a one-out walk to Matt Olson in the second.

Double plays in the third, fourth and sixth helped ease McHugh along when Oakland created traffic on the bases.

"The shift has been working the last two days big time," said Bregman, who finished 2-for-3 with a walk. "We work on it a lot during practice and before (batting practice). We take our work very seriously. (Shortstop) Marwin (Gonzalez) and (second baseman Jose) Altuve are doing a heck of a job turning double plays, so it's been fun to watch."

A nine-pitch fifth inning in which McHugh retired the side in order allowed him to complete the sixth and, despite some tense early moments, depart with a scoreless card and the lead.

"Just not very good swings at times," Oakland manager Bob Melvin said. "Got to give the pitcher some credit. He threw the ball pretty well but I expect us to hit some balls harder than we did tonight."

NOTES: With RHP Will Harris (right shoulder inflammation) and LHP Tony Sipp (right calf soreness) having faced live hitters Friday and C Evan Gattis (concussion) completing a position-specific workout, the Astros are poised to send all three out for a rehab assignment to Double-A Corpus Christi early next week. ... Athletics UTL Chad Pinder made his first career appearance in center field Friday night, shifting from right field in the bottom of the eighth inning. Oakland manager Bob Melvin acknowledged that Pinder could log additional innings in center over the final six weeks of the season. ... After exiting the game Friday night with a left hand contusion, crew chief Jerry Layne was back umpiring at third base. Layne was hit by a foul ball in the seventh inning in the series opener.