Shaun Marcum is an important piece of the Mets’ starting rotation, but a stalled bullpen session Monday left the team wondering if he will be ready to start the season.
Two major league sources told the Daily News that Marcum complained of neck discomfort Monday. That occurred during a bullpen session intended as a final check to make sure he was ready to make a Grapefruit League start on Thursday. According to the sources, Marcum is now highly unlikely to make that start.
Asked if Marcum’s readiness for the regular season next week was a concern, a source said, “That’s fair to say.”
Marcum’s agent, Rex Gary, did not immediately respond to a telephone message.
It is unclear who would take Marcum’s spot in the rotation if, as the team now fears, he is not ready for the season.

Lefthander Aaron Laffey, sent to minor league camp after a rough start on Sunday, had been considered next in line, but one source said that he “doubt(ed) it would be Laffey.”
Former Met Chris Young decided after starting for Washington Monday night to exercise an opt out clause in his minor league contract with the Nationals, because there was no room for him in the team’s rotation.
Mets people have been saying of late that they were not interested in a reunion with Young, citing confidence that Marcum, 31, would be ready - but that was before this latest incident. The Mets sent a scout to watch Young pitch four scoreless innings Monday against Houston in Kissimmee, Fla.
Marcum, who signed a one-year contract for $4 million plus incentives, has dealt with health issues for much of the spring. On March 19, the Mets sent Marcum back to New York for a cortisone injection in his right shoulder, saying that he had an “impingement.”