Lewis had to deal with this issue occasionally during his two-year stay in Japan in 2008-09, but this is the first physical setback he has experienced since re-signing with the Rangers. Since the beginning of 2010, Lewis has pitched 551 1/3 innings in the regular season and playoffs, the 10th most by any Major League pitcher.
"It's just tightness," Lewis said. "It was hard to get loose in the 'pen with cramping. It felt like everything was knotting up. That was the only issue. I don't even know how long it's going to be. It's all going to be based on how I feel when I come back and throw.
"I'll take today and probably tomorrow off and play some catch and see how it feels. I don't plan on missing more than two starts. That's the plan now."
Lewis was scheduled to pitch on Thursday, but Feldman will take that spot. The Rangers have not announced a starter for Saturday against the Athletics, but it could be Perez.
"It's a possibility," Daniels said.
Perez was called up on Tuesday to replace Lewis on the roster. Right now, both he and Justin Grimm will be in the Rangers' bullpen for the next few days. It will likely depend on how they are used -- if at all -- before Texas determines Saturday's starter.
"Today and tomorrow will determine that," Rangers manager Ron Washington said. "When we get the bullpen back together, then we'll make a decision."
Perez, who is ranked as the No. 2 prospect
in the Rangers' farm system, was 5-5 with a 4.59 ERA in 15 starts at Triple-A Round Rock. He has won his past two starts while allowing just two runs over 16 innings. He pitched his first career shutout in his last start against Iowa.
"He has thrown the ball well lately," Daniels said. "That's a credit to [pitching coordinator] Danny Clark and the guys down there who got him on a good program. Greg Maddux, [special pitching instructor], also worked with him. He's throwing a lot of strikes, attacking the zone and being very aggressive. If he can stay on the same path, he can really help us."
Grimm has made two starts for the Rangers. He beat the Astros in his Major League debut on June 16, when he allowed three runs in six innings. But he allowed six runs in one-plus inning in an 8-2 loss to the Tigers on Monday.
With Lewis down, the Rangers now have three of their Opening Day five-man rotation on the DL. Derek Holland has been sidelined since June 6 because of a stomach virus, but he's scheduled to throw 50 pitches in his first rehabilitation assignment on Wednesday for Round Rock.
He is scheduled to pitch again for Round Rock on Monday. The Rangers aren't sure if he'll need a third start in the Minors or be ready to rejoin the rotation during a three-game series with the Twins right before the All-Star break.
"It's a possibility," Daniels said. "When we drew the plan up, we were looking at three starts before he could come back. But given the nature of our situation, there will be some conversations."
Neftali Feliz has been on the disabled list since May 19 with a sprained right elbow. He has been throwing on flat ground, but has not yet started throwing off a mound. The Rangers don't anticipate that happening until the weekend before the All-Star break. He is eligible to come off the disabled list on July 18, but it will likely be closer to the beginning of August, given how much time he will need to build up his pitch count.
Daniels said the Rangers still aren't looking outside the organization for pitching help. The club signed right-hander Roy Oswalt in May, and he made his Rangers debut on Friday.
"If anybody has a setback or the prognosis changes on one or two guys, that might change," Daniels said. "But the group were getting back is more impactful than anybody that's out there. The real positive is all the guys should come back. We'll bide our time, weather the storm so to speak, and be in good shape when they come back."