JUPITER, Fla. -- Mets left-hander Jonathon Niese has been cleared to resume throwing after undergoing a favorable medical examination in New York.

Mets lefty Jonathon Niese has been cleared to resume throwing after undergoing a favorable medical examination in New York. AP Photo/Jeff Roberson

Niese underwent an MRI and was examined by team doctor David Altchek on Monday at the Hospital for Special Surgery in Manhattan, a day after departing a Grapefruit League game against the St. Louis Cardinals after two innings and 35 pitches because of elbow discomfort.

He described his MRI exam as "great news."

"It came back real strong," Niese said Tuesday, after returning to camp. "They said the UCL is strong and big and strong -- no bone arthritis or spurs or anything. So all the bones and ligaments are perfect. There's just a little inflammation in that joint in the back of my elbow. So I got a cortisone shot. It's a little sore today from the shot, but the soreness is going down. So I should be able to throw tomorrow. ... I doubt the mound, but I'll start throwing again."

He received a cortisone injection in the back of his left elbow to address inflammation but was informed his ligaments are fully intact. He is expected to resume throwing as soon as Wednesday.

"He sent [pitching coach] Dan [Warthen] a text this morning. He said they felt there was nothing and he'll be back on the mound here in a couple of days," manager Terry Collins said. "It was good to hear. Now we'll do a sigh of relief and come up with a plan to finish out the last two weeks with him."

Niese said the cause was overthrowing, according to the doctor's estimation.

"Altchek pretty much said that he thinks it's probably from trying to look at the radar gun -- overexertion, just trying to get that extra mile an hour," Niese said. "And all of a sudden mechanically you go the wrong way one time and all of a sudden it pinches and it's irritated. One thing I'm going to try to stop looking at this spring is the radar gun and just go by feel, because I know if I feel good the velocity is going to be there."

Still, the likelihood is Niese opens the season on the disabled list, while remaining in Florida to build up his innings count.

The Mets do not need a fifth starter until April 6, against the Cincinnati Reds at Citi Field. And that would be the day Niese would be eligible to be activated from the disabled list.

Placing Niese on the DL would allow the Mets to carry an extra bench player or, less likely, an extra relief pitcher for the first five games of the season. DL trips can be backdated nine days into spring training.

"I'd love to have him," Collins said. "But if we need to give him some extra days, it's no big deal. We can keep him back and let him pitch one more time down here." Collins previously has identified Bartolo Colon as the likely Opening Day starter if Niese were not ready, with Dillon Gee the alternative.

"There's no doubt we have to look in another direction. I'm not sure Jon is going to get the pitch count to where we need it to be," Collins said. "Probably by the end of the weekend we'll make that decision."

Niese was making his second spring-training trip to New York for an MRI. He also traveled to the Hospital for Special Surgery on Feb. 26 for an MRI of his pitching shoulder, which also revealed nothing alarming.

"I'm not sure how many MRIs you're allowed to have in a month before we start worrying about things," Collins said. "But his arm has been looked at in every which way and direction. There's certainly nothing in there."