TORONTO -- Miguel Batista officially was placed on the DL Sunday morning, with Chris Schwinden promoted from Triple-A Buffalo to take the roster spot ... at least for the day.

The team announced Batista has a lower-back strain, although the 41-year-old right-hander said the injury is more likely an oblique.

"It's more on the side, so it has to be an oblique," said Batista, who tried to warm up for the third inning Saturday wearing a belt to support his back, to no avail.

Jeremy Hefner "probably" will start Thursday against the San Diego Padres, his original club, at Citi Field, Terry Collins said. He would be the fourth person to occupy that rotation slot, following Mike Pelfrey, Schwinden and then Batista.

Batista said the injury is not severe, and he would have preferred to avoid the DL. But Collins said the Mets could not take the chance. After Batista departed Saturday's game, Hefner entered and limited the Blue Jays to two runs in five innings.

"I wasn't that sore today, but that's what they told me," Batista said about the DL trip. "I knew yesterday it wasn't a really bad one, but I felt a pull on that pitch. So far, hopefully it won't take 15 days. I don't believe it will. It all depends on how it goes tomorrow when I soft toss."

Said Collins: "He was pitching great. But he's got the groin issue. He's got the lower-back issue. He said his back feels a lot better today, and we understand that. But the one thing we can't afford to happen is in four days, or even tomorrow, 'Hey, look, I've got to back off my bullpen.' ... You end up having to pull him out of a game again after the second inning, we may not have the backup that's needed. We just thought in the best interest of letting his groin heal, letting his back heal, we'll disable him."

Collins confirmed the Mets would make another roster move before Monday's series opener in Pittsburgh to restore the bench to five position players. Utility man Vinny Rottino would be eligible, because Sunday is the 10th and final day he is required to be in the minors after being optioned to Buffalo on May 11. Schwinden would be logical to make a U-turn to Buffalo.