Tepesch allowed one run and two hits in 5 1-3 innings, striking out eight in his season debut in the majors. He was called up from Triple-A Round Rock earlier in the day.
“He did a good job. He really did,” Texas manager Ron Washington said. “He got us into the sixth inning and we had the pieces in the bullpen that we wanted in the game. We just didn’t shut them down.”
Tepesch thought he pitched OK, but is looking to improve.
“I was not getting ahead early and struggling with command early a little bit, but it did get better toward the end,” he said.
The Rangers used four relievers after his exit and all but Neal Cotts gave up at least one run.
“They just got us, and that’s all I can say,” Washington said. “They earned it.”
Dexter Fowler singled with one out in the ninth, Jason Castro drew a walk and Dominguez hit a long fly ball off Nick Martinez (0-1).
“Left the ball up that last pitch,” Martinez said. “Got deep in the count and left the fastball about belt high, so things happen. You have to learn from your mistakes.”
Chad Qualls (1-1) got the last two outs in the ninth for the win.
Alex Rios hit a solo homer, Adrian Beltre had three hits and Prince Fielder drove in two runs for Texas.