As BoxingScene.com previously reported, Vasiliy Lomachenko underwent right shoulder surgery on Monday.
Lomachenko will not be able to train until the early part of 2021.
The two-time Olympic gold medal winner, 32-years-old, had also undergone right shoulder surgery in 2018.
Last Saturday night at the MGM Grand's Conference Center, Lomachenko suffered his second career defeat when he dropped a twelve round unanimous decision to Teofimo Lopez.
The judges handed in scores of 116-112, 117-111 and 119-109 - with Lopez walking away with the IBF, WBC Franchise, WBO, WBA lightweight titles.
According to Lomachenko's manager, Egis Klimas, the boxer had pain in the right shoulder area as soon as he arrived from the Ukraine.
About six weeks out, Lomachenko was given an injection to eliminate the pain.
"We lost one week of training. We lost one week of sparring because the doctor forbid him to do much for a week after the injection," Klimas said to ESPN.
Weeks later, the pain returned and Lomachenko was given another injection.
The boxer's father and head trainer, Anatoly, wanted his son to withdraw - Lomachenko refused.
Klimas explains that Lomachenko's injury was more or less kept quiet to avoid the perception that his fighter was looking to make excuses.
There was no rematch clause in the bout agreement, and Lopez has rejected the idea of facing Lomachenko for a second time.
While there has been talk of Lomachenko moving back to super featherweight to pursue other avenues - Klimas indicates that his boxer is very much interested in securing the opportunity to regain his world titles.
Klimas is hoping that Lopez and his handlers come back to the table.
"If it's possible, we would like to have the rematch," Klimas said. "If they are so tough ... are they willing to come back and do that?"