The Rangers signed the 30-year-old as a free agent on April 27, 2012, after he was released by the Orioles. The Rangers are his fifth organization and he has pitched in 25 Major League games as a reliever. He pitched in 14 games for the Marlins in 2007 and 11 with the Athletics in '10. This will be his first Major League start.
"He is throwing the ball well," general manager Jon Daniels said.
The Rangers considered promoting left-hander Martin Perez, but he has made just three starts since returning from a broken arm and is 0-2 with a 9.49 ERA.
"We want Martin to have more time and be as ready as he can be," Daniels said. "Wolf was the recommendation."
Tepesch developed the blister in his last start against the Tigers on Friday night. The Rangers are not expecting it to be serious, and they are hoping Tepesch can pitch on Sunday against the Mariners.
"It's something we have to put behind us and get better," Tepesch said. "It popped up the other day. It's one of those things you have to take care to get ready so it doesn't come back.
"I've had a couple in the past, but I wouldn't really have a problem with them. It just has to get better and I'll be fine after that. It's one of those things you can't do a whole lot for. You just got to wait for it to heal, basically."
Weather permitting, Wolf will start on Wednesday, with Justin Grimm and Derek Holland scheduled to pitch the first two games against the Mariners on Friday and Saturday in Seattle. Tepesch would pitch on Sunday, meaning Yu Darvish will likely get an extra day of rest before his next start.
Darvish is expected to pitch one game of Monday's doubleheader against the D-backs in Arizona. Wolf is a candidate to pitch the second game, or the Rangers could recall either Josh Lindblom or Perez if needed. Right now, the Texas pitching staff remains unsettled with Colby Lewis, Matt Harrison and Alexi Ogando still on the disabled list.
"Everybody goes through it," manager Ron Washington said. "We'll battle through it and get back on track."
T.R. Sullivan is a reporter for MLB.com. Read his blog, Postcards from Elysian Fields, and follow him on Twitter @Sullivan_Ranger. This story was not subject to the approval of Major League Baseball or its clubs.