Doug Fister was waiting for a phone call in free agency this time last year after making 32 starts for the Houston Astros in 2016, the year before they won their first World Series.
The right-hander was the first of 166 major league free agents to finalize a deal this offseason, and now has a win over his old team to start 2018.
Fister tossed five effective innings in his Texas debut, Nomar Mazara homered for an early lead and the Rangers beat the Astros 5-1 on Friday night.
"I don't take any day for granted by any means," Fister said.
The 34-year-old Fister (1-0) limited Houston to Max Stassi's RBI double in the fifth in his second win in eight career starts in his new home ballpark, where he had an 8.73 ERA coming in. He gave up four hits, struck out three and walked three.
Four relievers finished the five-hitter, capped by Keone Kela pitching around a walk in the ninth.
Robinson Chirinos and Rougned Odor hit back-to-back sacrifice flies for a 3-0 lead in the fourth inning against 2015 AL Cy Young Award winner Dallas Keuchel. Chirinos' drive with the bases loaded was caught at the wall in right field by Josh Reddick.
Keuchel (0-1) allowed seven hits and three runs in six innings for the defending champs, who had a five-game winning streak against Texas after taking the season opener.
Mazara, who had one homer in 123 at-bats against left-handers last season, went deep in his first lefty-lefty matchup this season. The solo liner just to the right of berm in center field came in the second inning. He also walked and scored in the fourth.
"There's a few more hits to lefties than I would have liked," said Keuchel, who started 9-0 last year. "Made some adjustments and got through six but it was tough to see just based on how I felt going in and the matchup for me."
After facing a four-man outfield in four hitless at-bats on opening day, Texas slugger Joey Gallo had two hits, including an RBI double off the top of the wall in center, against a more traditional shift.
Chris Martin and Alex Claudio each had a bases-loaded strikeout to preserve a 3-1 lead in a bizarre sixth inning. The Astros loaded the bases after Odor threw about 30 feet wide of first in the middle of turning around on a botched double-play attempt that didn't get anybody out.
Jose Altuve was initially allowed to score when Odor's throw went into the Texas dugout but was called back to third on review. An earlier review that Mazara trapped Altuve's liner was upheld even though the replay appeared to show Mazara bending to make the catch after running too far back.
"I caught it, 100 percent," Mazara said. "It was a wild inning."
ON FURTHER REVIEW
Astros manager A.J. Hinch said he never got clarification on what the Rangers were looking for on the review of Odor's errant throw in the sixth. Odor's foot was barely off the bag as he barehanded a shovel toss straight from the glove of shortstop Elvis Andrus, who fielded a grounder by Alex Bregman up the middle.
Altuve was ruled safe at second on that part of the play, but then ordered back to third after being told to take home. Hinch said umpires ruled Altuve hadn't made it to second before Odor's wild throw. "There was a lot going on," Hinch said.
The Texas bullpen, a primary source of a disappointing season last year, is off to a strong start. Relievers have allowed two hits and one run with nine strikeouts in 7 1/3 innings.
Rangers: Lefty starter Martin Perez (recovering from right elbow surgery) and right-handed reliever Tony Barnette (lower back strain) pitched in an intrasquad game at Triple-A Round Rock on Friday night. Perez threw 87 pitches over six innings, and Barnette struck out all four batters he faced.
Astros: RHP Lance McCullers, the Game 7 starter in last year's World Series, is 0-3 in five career starts against Texas.
Rangers: LHP Matt Moore makes his Texas debut in the same park where he beat the Rangers in the 2011 Division Series with Tampa Bay.