They erred on the side of caution, and Lee said he can't argue with that. The Phillies placed Lee on the disabled list on Saturday, retroactive to April 19. He'll be eligible to return on May 4, when the Phillies play the Nationals.
"I feel like it should go away," Lee said. "But I've never dealt with anything like this before. It's something different. Hope we'll miss [only] a couple starts, and it's back to normal."
Lee sustained the injury on a pitch in the 10th inning of the Phillies' 1-0 loss to the Giants on Wednesday in San Francisco. He said he was unsure which pitch it was, but he didn't blame pitching 10 innings for causing the left oblique strain. He threw 10 scoreless innings, striking out seven and allowing seven hits. He's 0-1 with a 1.96 ERA.
"I felt fine the whole time," Lee said. "I threw 102 pitches. I've thrown more pitches than that in five or six innings. I don't think that had anything to do with it."
During his career, Lee has spent time on the disabled list for abdominal strains, but this injury is different. He went on the disabled list in 2003 for a strained lower abdominal muscle/hernia when he was with the Indians, in 2007 for a right abdominal strain when he was with the Tribe, and in 2010 for a right lower abdominal strain when he was with the Mariners.
"I've had ab strains, but nothing like this," Lee said. "It's on my left side. I felt a little something in the game, and I didn't think really much about it, to be honest with you. The next day, it was sore -- and when I threw, it lingered around."
Lee skipped his bullpen session on Saturday. He said he has been improving.
"The past couple of days it was pretty sore. But [on Saturday] it felt better than [it did on Friday]," Lee said. "We're heading in the right direction."
Right-hander Kyle Kendrick will start in place of Lee on Monday against the D-backs in Phoenix. Kendrick has posted a 1.93 ERA in four games this season. It will be Kendrick's first start of the season. Last year, he started 15 games and went 8-6 with a 3.22 ERA.
"I feel comfortable with Kendrick," Phillies manager Charlie Manuel said. "We've got the pitching to offset that. I've got a feeling [Lee] won't be out very long. When his time's up, he's going to be back."
The Phillies have recalled left-hander Joe Savery from Triple-A Lehigh Valley to fill Lee's spot on the roster.
Lee joins teammates Ryan Howard (Achilles surgery), Chase Utley (knees), Michael Martinez (right foot fracture) and Justin De Fratus (right elbow sprain) on the disabled list. Howard is expected to see a doctor on Monday and might be cleared for more baseball activities. The Phillies are expected to see Utley this week when they play Arizona. There is no timetable for Howard's or Utley's return. Martinez is in a walking boot, while De Fratus is on a rehab stint with Class A Clearwater.
The Phillies have to overcome injuries like Lee's, starting pitcher Roy Halladay said.
"Fortunately, we have Kyle down there -- who we all have confidence in and had a great spring. And [he] can step in, so that's a silver lining that we have that kind of guy down there," Halladay said. "But we want Cliff every start he can make. I think we're doing the smart thing taking care of it now, and he can progress later on."
Sarah Trotto is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.