As the New York Mets acquired second baseman Luis Castillo from the Minnesota Twins today, Martinez said he's ready for the next big step toward rejoining the rotation, making his first rehab start following shoulder surgery last fall.

At a news conference at the Mets' spring training complex, Martinez said he plans to throw 45 pitches Wednesday for the St. Lucie Mets and could make another start for the Class A team before determining the next step in his comeback.

"I don't know how I'm going to be," Martinez said. "I just know I feel better than the last two years or so. ... Every time I throw I bounce back really quickly. Right now, I'm 100 percent healthy."

The 35-year-old righty, a three-time Cy Young Award winner, had rotator cuff surgery last Oct. 5, and threw to batters on June 26 for the first time after the operation. The Mets hope to have him back in their rotation next month.

"My priority was to be healthy, and the only way I would find out if I was healthy was by testing myself all the time," Martinez said. "But at the same time, I've got no pressure. What could I do? I could say I'm hanging my cleats up and going home because my body's not responding. But it did, and so far it has."

Martinez was 9-8 with a 4.48 ERA in 132 2-3 innings last year but missed the postseason.

"I'm a very proud man when it comes to this job," Martinez said. "And my job is the most serious thing I could probably have right now apart from my family's health and my health. I feel like I owe it to this organization and to the fans."

New York, seeking its second straight NL East title, began the week with a 3 1/2-game lead over second-place Philadelphia. Atlanta, which was 4› games back, was on the verge of acquiring power-hitting first baseman Mark Teixeira from Texas before tomorrow's trade deadline.

Being away from the Mets has been difficult, Martinez said, even though teammates had told him to be careful and take his time.

"I know I miss them, and I miss being around the field and being around my teammates," he said. "It's been hard. It's been really hard, a lot harder than I thought."

Castillo fills a position that's been temporarily manned by Ruben Gotay following Jose Valentin's broken leg. Castillo adds speed to a batting order already topped by major league stolen base leader Jose Reyes.