YES Network.com

NEW YORK (AP) -- Johan Santana is going to have a MRI on his back, and his scheduled start Thursday might be in jeopardy.

The Mets had said Monday that Santana had some back stiffness but that it was not an issue, and that the left-hander's next start could be his final outing of the season.

But following New York's 3-1 loss to the Colorado Rockies on Monday night, manager Terry Collins said Santana tightened up after his bullpen session, and doctors wanted to examine him further.

His status for Thursday will be determined once the results of the exam are read.

Mets general manager Sandy Alderson said earlier Monday that he thinks the left-hander is good for one or two more starts but the situation will be reassessed around Sept. 1.