R.A. Dickey, the knuckleball pitcher who is the Mets de facto ace, left the game against the Cubs yesterday in the third inning with an injured right foot.

Dickey was running to cover first base on a grounder when he crumpled to the ground. He described the pain as a burning sensation in the heel, and he was later seen wearing a protective boot.

At this point, everything is speculation, he said last night. No one here is a doctor. It's just going to require some patience, and tomorrow we'll have a better idea what we're up against. I'm optimistic. I feel like I'm a pretty quick healer.

Coach Terry Collins feared it was an injury to Dickey's Achilles tendon, but that was later ruled out.

Dickey described the pain as like stepping on a railroad spike. Pat Misch is expected to take his place in the rotation.

The Mets went on to lose 9-3. Mets pitchers have allowed 33 runs in the last four games.