Oberholtzer has followed up a four-game winless stretch (0-1) with back-to- back wins over Oakland and Toronto and he bested the Blue Jays 8-2 on Saturday. He scattered a pair of runs, six hits and a walk over seven innings.
That improved the lefty to 4-1 with a 3.08 earned run average over his last eight starts and 4-7 with a 4.17 ERA on the season.
"(Oberholtzer) did a tremendous job," said Astros manager Bo Porter. "You're talking about a guy who is fearless. He attacks the strike zone."
The 25-year-old is aiming for his first win over the Rangers, having gone 0-2 with a 2.12 ERA in three previous encounters, including two starts.
Houston has won three in a row at home before getting swept in a three-game set at Philadelphia to begin the week. Thursday's 6-5 setback in the finale was the Astros' fifth straight on the road.
The Astros fell behind on Ryan Howard's two-out grand slam in the bottom of the eighth inning. Tony Sipp served up the game-deciding hit on a 3-2 fastball.
Sipp didn't think Howard's grand slam was going out.
"I knew it was high enough, but he just didn't drive it the way his balls usually go," Sipp said. "Obviously, he got it well enough. Off the bat, I thought it had a chance until the last minute."
Chris Carter went 3-for-4 with a pair of two-run homers and Marc Krauss added a solo shot for the Astros.
Houston aims to rebound tonight against Texas right-hander Miles Mikolas, who struggled in an earlier meeting this year with the Astros. That came on July 7 in his second career start and he was roughed up for nine runs and 12 hits in 3 1/3 innings.
Mikolas, though, is coming off one of his better starts of the season, though he still took a 2-0 loss to Cleveland on Saturday. However, the 25-year-old gave up just five hits and two walks over seven innings of two-run ball, striking out six.
Mikolas, 1-4 with a 7.29 ERA in six starts this year, is holding opponents to a .222 average over his past three starts against yielding a .375 average against in his first three.
"I threw a lot of strikes, I think," said Mikolas of his effort versus the Indians. "A lot of things we worked on in that last bullpen (session), everything started to come together. I felt like I threw a lot of quality strikes. I went right after the hitters."
Texas is 2-4 on a nine-game road trip, picking up consecutive victories over the Chicago White Sox to close a three-game set. The Rangers' 3-1 win on Wednesday gave them their first winning streak since June 27-28.
Adam Rosales homered twice, a two-run blast in the second and a solo shot in the seventh, while Nick Tepesch scattered six hits over 5 2/3 scoreless innings.
"We didn't know what Tepesch would give us after having 10 days off, but today he stayed focused and executed his pitches," Rangers manager Ron Washington said. "He did a great job."
The Astros, who swept a three-game set in Arlington in the last meeting from July 7-9, have won six of nine versus the Rangers this year.