CINCINNATI -- The Mets' rotation has been revised again to accommodate Pedro Martinez, though this time his unavailability diminishes the Mets in a different way.

Martinez received a cortisone injection on Thursday to eliminate inflammation and promote healing in his right groin. Both the injury and the shot have forced the Mets to postpone Martinez's next start until Tuesday, at the earliest.

Moreover, his absence eliminates Mike Pelfrey, the Mets' most effective starter of late, from the team's series against the Phillies at Shea Stadium next week.

Martinez initially -- and tentatively -- had been scheduled to start against the Reds on Sunday in the fourth game of the series that began on Thursday night. Under that scenario, Pelfrey would have started on Tuesday in the first of the three games against the Phillies. Now Martinez, with his health and stamina game-to-game issues, will start against the team that is the primary obstacle to the Mets' postseason hopes.

Martinez sustained the groin injury running the bases on July 7, and the strain interfered with his delivery in his most recent start, on Saturday. After altering his delivery, he developed tightness in his shoulder and was removed after four innings.

He had flown to the Dominican Republic on Sunday to be with his father, who is seriously ill, and received the injection on Thursday in New York. The Mets said they had waited until Thursday to be certain that cortisone treatment was essential, as players are typically told to rest for 48 hours after receiving such an injection.

Manager Jerry Manuel said on Thursday that Martinez will rejoin the team and throw in the bullpen on Saturday. If problems develop and he becomes unavailable, the team will skip his turn on Tuesday, Monday's off-day making that possible. Manuel doubted that Martinez -- who missed two months with a left hamstring injury after starting the second game of the season -- would be assigned to the disabled list.

"The only time I've been concerned [about Martinez] was when he mentioned the shoulder thing that one game," Manuel said. "Other than that, I haven't been concerned. I don't really see him as a complete-game guy anymore, you know. I think that would be unrealistic. But I do see him as being a guy that can help us win a division."

Martinez, who has a 3-2 record and 6.25 ERA, has made nine starts and pitched just 44 2/3 innings.