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7/19/2014 7:53 P.M. ET

Oberholtzer to start Tuesday in Oakland

CHICAGO -- Manager Bo Porter has shuffled his pitching rotation for the Astros' upcoming series in Oakland.

Brett Oberholtzer will start Tuesday's series opener, and will be followed by Brad Peacock and Scott Feldman on Wednesday and Thursday, respectively.

Right-hander Collin McHugh was slated to make his return from the 15-day disabled list on Tuesday after sustaining a middle finger nail avulsion on his pitching hand, but will instead make a rehab start that day with Triple-A Oklahoma City.

The decision came after McHugh threw a bullpen session in Chicago on Friday. Porter didn't say if McHugh tweaked the injury during the session, but said he didn't want to rush the righty back.

"He had to come out of the game because of the finger the last time," Porter said. "Obviously, that led into the All-Star break and we had more time to give it time to heal and we knew we were going to have a longer break, so we weren't at risk of our bullpen getting taxed at that time. Whereas, when you look at it being the first game of a series and we don't have an off-day within that stretch, we'd rather him make a rehab start [and] know that there's no ill effect, no setback. Then we'll put him back in the rotation after that."

Porter didn't indicate when McHugh might make his big league return. The Astros have six players on the disabled list or out for the season.

Gonzalez, Hernandez to balance time at shortstop

CHICAGO -- Astros manager Bo Porter likes what he's seeing from Marwin Gonzalez, the utility man who has primarily played shortstop.

Gonzalez has started in 39 of the 62 games he's played this season, 28 at shortstop.

Porter said the switch-hitting Gonzalez, now in his third year, is in "a more everyday role" but that he will utilize righty Enrique Hernandez against southpaw starters.

"When I get an opportunity to play [Hernandez] at short, it will probably be against left-handed pitching, and give Marwin the day during that time and get another one of my right-handed bats in the lineup," Porter said. "But Marwin will play the bulk of the innings and bulk of the games at shortstop."

Hernandez has played all over for the Astros since being called up on July 1, with stints at second base, shortstop, left field and center field. Porter said Hernandez could even play third base if needed, though Matt Dominguez has played there in 92 of the Astros' 97 games this season.

"[Hernandez] has moved all around the diamond," Porter said. "Even the day I put him out in center field, I asked him, 'Can you play center field?' and he said, 'Skipper, I'm a baseball player.' From a manager's standpoint, that's the answer you love to hear. I'm comfortable putting him anywhere on the diamond. He's confident with his glove. He's got plus arm strength and he's a heads-up, smart player."

Hernandez played shortstop in Friday's series opener against left-hander Jose Quintana, but returned to left field Saturday against righty Hector Noesi.

Worth noting

Notre Dame outside linebackers coach Bob Elliott was in the Astros dugout before Saturday night's game, sharing laughs and memories with Porter. Elliott coached Porter when he was a standout defensive back for the Iowa Hawkeyes, and joked that had Porter stuck with football, "he'd be the oldest safety in the NFL right now."

Daniel Kramer is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.