PORT ST. LUCIE, Fla. -- Mets pitcher Zack Wheeler, who has spent nearly two full years attempting to return from Tommy John surgery, felt some "tenderness" in his right elbow during a routine bullpen session earlier this week, according to pitching coach Dan Warthen. The Mets have briefly paused Wheeler's throwing program as a result.

Warthen was quick to add that he does not consider this a setback for Wheeler, because a routine physical exam taken Monday revealed no structural damage. The team believes Wheeler's discomfort stems from scar tissue that formed in his elbow following a platelet-rich plasma injection last August. The club also hopes Wheeler can play catch Thursday and return to a mound as soon as Friday.

Still, the Mets plan to treat Wheeler with extreme caution. He is battling Robert Gsellman and Seth Lugo this spring for the final spot in New York's rotation.

"We're not going to push it because we want to see this kid be healthy," Warthen said. "And once he gets healthy, we want him to stay healthy. We will have kid gloves with him."

Though Wheeler has been throwing regularly since reporting to Port St. Lucie earlier this month, he did not play catch with his teammates on Tuesday and Wednesday. Wheeler has not made it back to game action since undergoing Tommy John surgery in March 2015. Last April, he underwent a second surgical procedure to remove an undissolved stitch from his throwing elbow, before suffering multiple setbacks -- including a flexor muscle strain that prompted the PRP injection, effectively ending his season -- over the course of the summer.

But the Mets' hope was that Wheeler would return to spring camp healthy, ready to join Noah Syndergaard , Matt Harvey, Jacob deGrom and Steven Matz on the Opening Day roster. Those five have never all been in the rotation at the same time.

"We have to be careful when he's throwing next to the rest of those guys because he wants to be one of the five," Warthen said. "You can't blame him for that because he earned it a long time ago. But we've just got to be extremely careful of this kid because it's a special arm, and it needs to be healthy when he gets back."

The sixth overall pick in the 2009 Draft and once one of baseball's most promising pitching prospects, Wheeler went 18-16 with a 3.50 ERA from 2013-14. Even if he makes it into the rotation this summer, Warthen said, the Mets plan to restrict Wheeler to an innings limit "in the low 100s." That means limiting him to five innings per start, with a maximum of 25 starts.

An alternative involves sending Wheeler to the bullpen to open the year. But Warthen is among a group of Mets officials who consider that a dangerous gamble, knowing Wheeler's injury history.

For now, the Mets will simply watch Wheeler carefully, giving him extra rest whenever they feel he needs it.

"I'm not getting my hopes up one second," Wheeler said earlier this week. "I hope I'm good. I hope I'm ready. I've done everything that I could."

Anthony DiComo has covered the Mets for MLB.com since 2008. Follow him on Twitter @AnthonyDiComo and Facebook, and listen to his podcast.