Ki Sung-yueng will return to his homeland of Korea earlier than scheduled as he prepares for the World Cup.
The 25-year old Swansea City midfielder, who has impressed on loan for Sunderland this season, has not played for the Black Cats since April 12 because of tendonitis in his knee.
Ki has been ruled out for the remainder of the campaign and according to the Chosun Ilbo, will head back to Korea to undergo treatment in order to have him fully fit ahead of the 2014 World Cup in Brazil.
Poyet said that Ki would not feature in Sunderland's final three fixtures of the Premier League season, revealing that the former Celtic star had headed to London for specialist treatment.
"I really don't know if it will be possible for him to play again for us," Poyet told the Southwest Evening Post.
"Ki has been to see a specialist in London who has confirmed that it is tendonitis of the knee and needs to be treated carefully. It's not something that has come on suddenly, he has had a problem with it for a while."
