Pedro Martinez is getting closer to a return to the Mets' rotation. The ace threw a three-inning, 50-pitch simulated game in Port St. Lucie yesterday, using all his pitches and fielding his position - a step forward from his batting practice sessions. Assistant GM John Ricco said Martinez will now be given a seven-to-10-day layoff from pitching to "rest his body and mind after nine months of extremely hard physical and mental work" following surgery last Oct. 5 to repair a torn rotator cuff. Martinez then may be ready to begin a rehab assignment in the minors that can last no longer than 30 days. The alternative would be to pitch in another simulated game, which would increase his innings and pitch count. Ricco said the organization's estimate of an August return still holds.