New York Mets right-hander Noah Syndergaard underwent successful Tommy John surgery on Thursday, a source tells ESPN.

The Mets announced Tuesday that Syndergaard would need the surgery. He is expected to return sometime during the 2021 season.

Syndergaard, 27, who is one of the hardest-throwing starting pitchers in baseball history and has among the best arsenals of pitches in the game, was expected to anchor the Mets' rotation alongside ace Jacob deGrom.

Syndergaard threw a career-high 197 ⅔ innings last season, and while his ERA was a career-worst 4.28, the combination of good health and stuff foretold good things. However, he has had a tough time staying healthy.

Injuries wiped out most of Syndergaard's 2017 season and shortened his 2018. This season he planned to join deGrom and Marcus Stroman atop the Mets' rotation, with Steven Matz, Rick Porcello and Michael Wacha filling out the last spots.

Syndergaard, acquired by the Mets in 2012 when they traded Cy Young winner R.A. Dickey to Toronto, was an instant phenom. His fastball consistently hit 100 mph, he ripped off sliders as fast as 93 mph, and he struck out 166 batters in 150 innings as a 22-year-old rookie in 2015. His best year came in 2016, when he was an All-Star and posted a 2.60 ERA in 183 ⅔ innings.