HOUSTON -- Steve Pearce, acquired off waivers from Baltimore by the Astros on Saturday, was originally not scheduled to start Sunday against the Pirates. But after the Astros traded Chris Johnson to the D-backs, Pearce was starting at first base in his Astros debut.

He recorded his first hit for Houston on a fifth-inning double.

Manager Brad Mills said he doesn't envision using Pearce as an everyday player, but he can play the corner spots in the outfield, as well as first base.

"He will get plenty of playing time," Mills said.

Pearce was hitting .254 with four doubles, three homers and 14 RBIs in 28 games for the Orioles this year. He began the season with Triple-A Scranton/Wilkes-Barre in the Yankees organization, hitting .318 with 11 homers and 30 RBIs before being traded to Baltimore.

"I talked to the manager, and he said there's an opportunity here," Pearce said. "I look forward to being here. I'm happy to be back here in the this league and just have to take advantage of the opportunity."

Wallace recalled from Triple-A; Bixler optioned

HOUSTON -- The Astros called up infielder Brett Wallace after Sunday's win over the Pirates, optioning infielder Brian Bixler to Triple-A Oklahoma City.

Wallace, 25, will play first and third base with the team. He is also considered an option at shortstop should current starter Marwin Gonzalez get injured. Manager Brad Mills said infielder Matt Downs is also an option.

"I think if something happens with [Gonzalez], I don't have any problem at all putting those guys out there for a few innings," Mills said. "Then we'll go from there."

In 36 at-bats with the Astros earlier this season, Wallace batted .333/.426/.583 with two homers and four RBIs. With Oklahoma City, Wallace was batting .300/.379/.506. Over his last 10 games, Wallace was 11-for-32 with two homers and eight RBIs.

Wallace played nine games at shortstop with Oklahoma City. He has no other shortstop experience in the Minor Leagues.

Bixler, 29, batted .193 in 88 at-bats for the Astros.

Worth noting

• Mills said catcher Jason Castro, who's been out since July 8 with a sore knee, could be headed to Kissimmee, Fla., this week to continue his rehab at the Astros' Spring Training facility. There are plenty of bodies there, as the Astros' Gulf Coast League club calls it home.