Johan Santana isn't officially done for the season yet, but signs point to the Mets left-hander at minimum missing his scheduled start Thursday against the Rockies.

After experiencing lower-back soreness during a Monday bullpen session, Santana underwent an MRI exam Tuesday— the results of which the Mets say they won't receive until Wednesday — at the Hospital for Special Surgery in Manhattan.

The flare-up came after manager Terry Collins and general manager Sandy Alderson declared Santana fine to make at least one or two more starts this season, beginning with Thursday.