"Just similar to last year ... something I have had, and it comes up once in a while," Hamels said. "You get in more stressful situations and start exerting too much, with my long strides, it happens. I don't want it to linger. Getting 34-35 starts is key, and I don't want to have something to keep me from being at my best."
The Rangers will replace him with left-hander Cesar Ramos, who was 0-1 with a 3.18 ERA in three starts at Triple-A Round Rock. This will be his first Major League start since May 17, 2014, while with the Rays.
Rangers manager Jeff Banister said he would prefer a left-hander against the Yankees and a lineup that includes lefty hitters Jacoby Ellsbury, Brett Gardner and Brian McCann.
Hamels last pitched against the Orioles on Wednesday, allowing one run in 6 2/3 innings. He threw 106 pitches, but said he doesn't remember straining the muscle on any particular pitch.
The muscle ached after the start, and he didn't feel confident enough to throw his normal between-start bullpen session either Friday or Saturday. He has been able to play catch, but he's not ready to throw off a mound.
The Rangers feel confident that Hamels won't need to go on the disabled list.
"Based on the medical assessment and his experience, all those factors, I trust what Cole is telling us," Banister said. "It is something he has had to battle through. Let's be smart and conservative and make sure it doesn't affect anything else. We'd rather give him extra time now and not create a bigger situation."
Hamels is 3-0 with a 2.52 ERA in his four starts.
• Pitcher Yu Darvish is scheduled to throw 60 pitches in a live batting practice session on Monday. If all goes well, he could start a rehab assignment next weekend in Frisco.
• Outfielder Josh Hamilton was 2-for-5 as a designated hitter in an extended spring workout game on Saturday. Chris Gimenez was 2-for-4 with two doubles and a walk. He also caught three innings.
• Ian Desmond had a home run, three walks, three runs scored and two stolen bases on Saturday. He is the first Rangers player to have such a hitting line.