HOUSTON -- Roy Oswalt threw 25-30 pitches on flat ground Monday and said later he felt confident he would make his scheduled start Thursday against the Phillies.

After he was examined by team medical director Dr. David Lintner later that evening, the club confirmed the right-hander would indeed remain in the rotation.

Oswalt left his most recent start on Saturday against the Rangers in the seventh inning with what was originally announced as a right groin strain, but the right-hander says the pain is in his inner right hip. He intends to test the area again Tuesday with another long-toss session but doubts he'll have to skip a start in order to heal.

"It's not a muscle strain, so that's a good thing," he said. "I think it's more of a tendon ... I think it's just inflamed more than anything."

Oswalt speculated this could be a result of being hit twice in that area with batted balls this season. He's also relieved it's not a groin problem, which hampered him several times during the 2003 season and eventually required surgery.

"I knew this wasn't muscular," he said. "The years I had the groin [strain], once I felt it, I was done. This, I could actually pitch through it. Just an achy feeling more than anything."