Zack Wheeler had hoped to be on a pitching mound in Port St. Lucie, Florida, by Wednesday. Instead, he will be in Manhattan getting his right elbow checked out at the Hospital for Special Surgery.

Wheeler, who had Tommy John surgery in March 2015, is experiencing “discomfort,” Mets manager Terry Collins announced Tuesday.

The Mets originally hoped to get the righthander back in the major-league rotation by July 1. Then the timetable was modified to after the All-Star break after Wheeler underwent a procedure to remove an undissolved stitch from the original operation. Now, the Mets are holding their breath that the 26-year-old will not have to be shut down for an extended period. Wheeler was supposed to throw an inning in a simulated game this week in what would have been his first outing since the surgery.

“All I can say is he’s had a little bit of elbow discomfort,” general manager Sandy Alderson said. “He hasn’t thrown in a couple of days and he’s going to be seen here in New York (today).”

Asked his level of concern, Alderson said: “We’ll know (today). Have a better understanding.”

The Mets had hoped Wheeler could give the rotation a mid-season boost, which would allow them to move Bartolo Colon to the bullpen. In his first two big-league seasons, Wheeler went 18-16 with a 3.50 ERA.

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The Mets did get some good injury news about another of their prized young starters. Steven Matz, who felt elbow tightness during his last start Saturday, has been OK’d to start Friday in Atlanta.

The Mets placed righthander Jim Henderson on the 15-day disabled list with right biceps tendinitis. Collins admitted the team is concerned about Henderson’s surgically repaired shoulder.

Lefthander Sean Gilmartin was recalled from Triple-A Las Vegas, although he is not expected to be available for at least two days after he threw 100 pitches on Sunday.