PORT ST. LUCIE, Fla. -- When the Mets closed camp on March 2, pitching coach Dan Warthen urged his hurlers to take advantage of the day, even though three off-days were scheduled for the remainder of the spring.

"They won't be off-days," Warthen said. "Not really."

No game was scheduled Wednesday. So call it an off-day and understand not everyone one was off. Warthen and manager Jerry Manuel monitored Mike Pelfrey, the strained muscle in his left leg healed, as he threw a bullpen session without limitations in the morning. And they watched Jon Niese and his curveball bury a lineup of Mets Minor Leaguers.

Pelfrey now is in line to rejoin the rotation in proper sequence. The righty is to start against the Nationals on Saturday in Port St. Lucie. He will follow the first exhibition-game start of Johan Santana by two days. And unless the sequence of starters unravels between now and Opening Day (April 6), Pelfrey will follow Santana by two days and start the second game of the season on April 8.

Pelfrey's injury -- characterized as unusual by the trainers -- is no longer an issue.

"I felt it a little bit, but it's a lot better," he said. "If it was the regular season and I had to pitch today, I would've."

But Pelfrey had said the same thing Saturday before the injury was diagnosed.

Jon Niese pitched four innings -- the first three were perfect -- as part of his continuing audition for the No. 5 spot in the rotation. He allowed a walk and a hit that might have been scored an error if the game had been official. Niese will throw again Monday on another off-day.

Niese, his curveball already a big league pitch, has worked with Warthen and John Franco on his changeup. Franco, of course, made a living with his changeup.

"John put it perfect," Niese said. "It's like as soon as I want to throw a changeup, it's not a changeup. I've got to throw it like a fastball with a changeup grip."

Or as Franco says, "Just throw a fastball with a changeup grip, and that's a changeup."

Franco learned his changeup from Dave Wallace, later the Mets' pitching coach, when he and Wallace were with the Dodgers in the 1980s. After Franco moved to the Reds during the '83 season, former Reds starter Fred Norman helped him refine the pitch.

In other Mets news, Angel Pagan underwent arthroscopic surgery in New York on Wednesday to remove a bone spur from his right elbow. He is to miss six to nine weeks. Nine weeks without playing would take him beyond the one-year anniversary of the shoulder injury that ended his 2008 season. Injured in Los Angeles on May 7, Pagan, 27, didn't play after May 12.