NEW YORK -- Yankees starter Nathan Eovaldi will need to undergo Tommy John surgery for the second time.

Eovaldi, who was placed on the 15-day disabled list on Friday after he left in the first inning of his start against Boston two days earlier, announced Tuesday that he has torn the flexor tendon off the bone and damaged the ulnar collateral ligament in his throwing elbow.

The injury will require two surgeries -- one to repair the flexor tendon and the other a replacement of his UCL with a tendon from elsewhere in his body.

The estimated rehab time for the flexor tendon surgery is between three and six months. However, being that this is Eovaldi's second Tommy John surgery -- he had his first such surgery nine years ago as a 17-year-old high school pitcher -- the rehab process is likely to be a bit longer than usual, possibly up to 18 months.

"It's a huge blow," Eovaldi said. "It's my second one, so it's a big deal. Hopefully everything goes well with the surgery and I work hard to get back."

Eovaldi said there had been no discussions between him and doctors about the possibility of these injuries ending his career. That said, he has been advised to be "a little more safe" with the rehab given that it is his second time.

In all likelihood, Eovaldi won't return until the 2018 season, but he was told there is a chance of him returning to pitch from the bullpen in the last month or two of '17. Eovaldi is under team control until '18, but he is arbitration-eligible in '17.

Unlike the first time Eovaldi underwent elbow surgery, the hard-throwing right-hander said he didn't feel much pain this time around. While he described his first injury as "the worst pain" he's had, this injury was more of a slight inconvenience.

"It wasn't a particular pitch or something like that," Eovaldi said. "I just felt a little pinch every time I threw a fastball. After the first inning [in his most recent start], my velocity was down a little bit, but I didn't feel like there was anything to really worry about. But then I got the MRI, and when I got the results, I was really surprised to see that I had torn the flexor tendon off the bone and damaged my UCL."

While it isn't uncommon for a pitcher to have Tommy John surgery twice, it does make it significantly more difficult to come back, especially as a starter. Relief pitchers such as Joakim Soria , Joe Nathan , Jason Isringhausen and Eric Gagne have worked their way back into the Majors after two surgeries, but success stories among starters are more difficult to find. That said, pitchers like Kris Medlen and Chris Capuano have succeeded in back-to-back rehabs.

Eovaldi's 2016 season was marked by inconsistency. He posted a 4.76 ERA in 21 starts and three relief appearances. In his nine wins this season, Eovaldi had an ERA of 1.72, but in his 15 other appearances, his ERA was 7.17.

Nick Suss is a reporter for MLB.com based in New York.