Mets manager Jerry Manuel was unsure when Rodriguez would be available, but expects shortstop Jose Reyes to play Monday at home against the Nationals. Reyes has been sidelined with tendinitis in his right calf.
Manuel said after Saturday night's game that Rodriguez couldn't walk following batting practice. The right-hander said "his legs locked up," prompting medical personnel to take him to an ambulance on a stretcher.
"That was scary," Rodriguez said on Sunday, talking to the media with his back wrapped while the Mets took batting practice before their game against the Red Sox. "I've never felt anything like that.
"They gave me some medicine and it feels better."
A three-time All-Star who saved a major league record 62 games for the Los Angeles Angels last season, K-Rod came to the Mets for a three-year, $37 million free-agent contract as the centerpiece of an offseason bullpen overhaul.
He is 12 for 12 in save opportunities, including a perfect ninth on Friday night against Boston, and is 1-0 with a 0.87 ERA in 20 games this season.
J.J. Putz pitched in the ninth on Saturday to close out the 3-2 victory over Boston.