Tepesch had retired the first two batters of the second inning before Mariners catcher Jesus Montero lined a single up the middle that hit the 24-year-old right-hander in the right wrist/forearm area. Blood was visible on Tepesch's right arm.
X-rays on Tepesch's wrist were negative, and Rangers manager Ron Washington expects him to make his next start.
"He really wasn't saying anything," Washington said of when he rushed to the mound to check on his pitcher. "He wasn't showing any emotion. He was walking around because I'm quite sure it was hurting. He got on the mound and he threw and in actuality he thought he could finish. But we weren't going to take that chance."
Tepesch, who did have some swelling in the wrist, said it's not too bad.
"I'll just start preparing for the next start," said Tepesch, who planned to get more treatment on the wrist, including icing it. "It was a little sore. It could have been a lot worse."
Tepesch, making his third career major league start, struck out three of the first five batters he faced. He was replaced by veteran Derek Lowe, who pitched four hitless innings of relief in an eventual 5-0 victory.
Tepesch is the second Rangers pitcher to be injured by a line drive by a Mariners hitter this year. Left-hander Martin Perez broke his left wrist in a spring training game against Seattle. Perez is rehabbing at the club's extended spring training in Surprise, Ariz.
The Rangers lost Opening-Day starter Matt Harrison until after the All-Star break because of pending back surgery for a herniated disk.