HOUSTON -- Astros rookie Myles Straw, who appeared in 39 games with the club earlier in the season, will make his first career Major League start at second base in the second game of Tuesday’s doubleheader. Straw was called up from Triple-A Round Rock as the team’s 26th player, making him eligible to play only in the second game of the doubleheader.

The speedy outfielder has taken to the infield this year and started 13 games at shortstop for the Astros, in addition to his time in Round Rock. He’s only started two career games at second base, both coming within the last week at Triple-A.

“I don’t really have a lot of concern with him playing second,” Astros manager AJ Hinch said. “I wanted to make sure we brought a position player to alleviate a little bit of the next 24 hours. In choosing which guys and where he was going to play, I didn’t want to play [Aledmys] Diaz back to back games even though he might end up doing it anyway.

“Myles will be fine at second. We’ve worked with him a lot and he’s played a little bit of that position at Triple-A. The way we shift, he’s played on the second-base side of the infield and as I’ve told a lot of people, if I can start him at shortstop for a [Justin Verlander] start or a [Gerrit] Cole start, I’m not sure that I need to worry about him at second.”

Peacock headed back out on rehab

Veteran right-hander Brad Peacock rejoined the team Tuesday in Chicago after making four rehab outings at Triple-A Round Rock while he recuperates from right shoulder soreness. But he’s not ready to be activated just yet.

Hinch said he told Peacock he felt he needed one or two more outings at Triple-A, which means Peacock will be headed back out to rejoin Round Rock and continue his rehab. Peacock, who’s going to be used in relief when he’s activated, allowed two hits and two walks in his outing Sunday in Albuquerque and didn’t record an out, but he said he was healthy.

“He feels tremendously well, which is good,” Hinch said. “The ball’s coming out pretty good. It was 94 [mph] last outing. The transition to the bullpen, we want to be very, very particular what our plans are for him. He’ll get another one or two rehab assignments before we consider activating him.”

Peacock was in good spirits, despite Sunday’s rough results.

“I felt great, man,” he said. “It’s Albuquerque. It’s a tough place to pitch. I have nightmares from that place, but I felt really good.”

Astros need starter for Saturday

With Zack Greinke and Gerrit Cole both pitching in Tuesday’s doubleheader, the Astros will be in need of a starting pitcher for Saturday. Greinke was originally scheduled to pitch Saturday in Oakland, but Monday’s rainout pushed him to Tuesday and he won’t come back on three days of rest.

Hinch said the likely candidates to come up from Triple-A are Rogelio Armenteros and Framber Valdez. Armenteros has allowed three earned runs in 14 innings in four outings (one start) for the Astros, while Valdez has a 5.58 ERA in five starts for Houston earlier this year. Jose Urquidy, who went 1-1 with a 5.87 ERA in five starts for Houston, was scheduled to start Tuesday at Round Rock and is likely not available to pitch again Saturday.

“It depends how the next three or four days go,” Hinch said.