PHILADELPHIA -- The Mets are planning to fill a vacancy in their starting rotation with one of the game's top prospects, handing right-hander Noah Syndergaard his Major League debut on Tuesday against the Cubs at Wrigley Field.

Right-hander Dillon Gee was formally placed on the 15-day disabled list with groin pain Saturday afternoon, clearing a spot for Syndergaard, considered the Mets' No. 1 prospect and the No. 11 prospect in baseball.

Syndergaard throws eight-inning gem ... and homers

Gee originally felt discomfort in his groin during his last start. On Friday, the discomfort remained during a side session, and the Mets decided the best option was to place Gee (0-2, 3.86 ERA) on the 15-day DL retroactive to his last start -- a 1-0 loss to Washington.

"I was hoping worst-case scenario would be getting pushed back a day or two," said Gee, who surmised possibly having an MRI and a cortisone shot and, after a few days of rest, getting back to work. "But I think we take a page out of last year. I think we play it safe.

"The last thing I want to do is go out there and be out another month. I have 10 days, and hopefully it's over."

"On Sunday he suffered what we would call a mild groin strain," Mets general manager Sandy Alderson said of Gee. "He threw a little bit today, and it was still there. So he definitely would not pitch on Sunday. Given the uncertainty of the groin, we decided to retroactively put him on the DL from Monday."

Video: [email protected]: SNY gives an update on Syndergaard's status

To fill his roster spot, the Mets will call up Syndergaard from Triple-A Las Vegas. Syndergaard, 22, went 3-0 in five starts with a 1.82 ERA with Las Vegas. In 29 2/3 innings of work, he struck out 34 and walked just eight. He will join the Mets on Saturday, throw a side session and then get the start on Tuesday in Chicago.

"[Syndergaard] is a year-plus in Triple-A, and he's certainly done a nice job given his last three starts he's been overpowering. From that standpoint, he's deserving," Alderson said.

The Mets had already planned to adjust their rotation as they embark on a 20-games-in-20-days stretch, but Gee's injury accelerated their plan. The Mets will move both Bartolo Colon and Jacob deGrom up a day but both will remain on regular rest after an off-day Thursday.

"We set this up a while ago when we looked at the schedule," manager Terry Collins said. "We're trying to make sure that we don't overuse some of these guys. If you can keep your starters healthy, and run them out there basically every five days, or every six days -- I heard it a long time ago, the healthiest staffs in baseball win. Not always the best."