LAKELAND, Fla. -- Magglio Ordonez believes he'll be able to play in the Tigers' season opener Monday after receiving treatment for what doctors believe is a case of diverticulitis.

"Monday, I think I'm going to be ready," Ordonez said Thursday morning after he reported to the clubhouse. "Today, I feel much better."

Diverticulitis results from an inflammation of the walls of colon when it becomes infected or inflamed. It can be painful, as it has been for Ordonez, but can be treated with medication or, in some cases, changes in diet.

Ordonez said he started feeling pain in his stomach last week and estimated he's lost three or four pounds. The pain became more pronounced Monday night and into Tuesday, when he went to see a doctor to undergo tests. Doctors prescribed him with medication.

"The last week I've been feeling kind of weak," Ordonez said. "I feel a pain here in my stomach."

Manager Alan Trammell said Tuesday that Ordonez was receiving a day to rest, but did not say whether he was physically OK. Trammell said Wednesday that he did not know the exact nature of Ordonez's ailment the previous day.

"It's nothing that big." Trammell said. "But, obviously, Opening Day is a big day."

Ordonez said he still feels weak, but he raised hopes that he'll be able to play Monday when he looked fine taking batting practice Thursday morning. He'll be held out of the Tigers' final Spring Training games Thursday and Friday, as well as Saturday's exhibition at Philadelphia.

Up to this point, the only question involving Ordonez's health had been his surgically repaired left knee, which suffered two separate meniscus tears last summer. His knee has had no setbacks this spring, and he's been able to play right field regularly since missing the first week or so of games as a precaution.

Ordonez's presence is a major addition to the Tigers' lineup. The last prominent free agent to sign this offseason, Ordonez became Detroit's new cleanup hitter with a five-year, $75 million contract. He's hit .267 (8-for-30) this spring with two home runs and nine RBIs in 12 games.