Kevin De Bruyne has completed his move to Chelsea but he will stay with Genk on loan until the end of the season.
De Bruyne, who has been a long-term target of the Blues, travelled to London on Monday to undergo a medical and Genk have confirmed the 20-year-old put pen to paper early on Tuesday morning.
The deal will see the winger commit to Chelsea until 2017 but the terms of the agreement mean he will remain with Genk until the summer.
"The transfer of Kevin De Bruyne to Chelsea has been completed. He has signed for five and a half seasons and will continue (playing with) Genk until June," a statement on the Genk website read.
"His signature was confirmed at 0.30 last night. De Bruyne and his agent will return back today from London, along with general director Dirk Degraen.
"Genk will hold a press conference with (director) Jacob Gunther and Dirk Degraen in which they will clarify the transfer policy.
"Afterwards, Kevin De Bruyne will also give an explanation about his transfer to the English club."
It is unclear how much Chelsea have paid for De Bruyne but reports have suggested the Blues have handed over STG7million.
"It's a little bit of a dream come true. I've worked very hard and am still very young but have already played a lot of games. To come to a team like Chelsea is a dream but now it's a reality and I have to work hard to achieve the level that's necessary," De Bruyne said.
"I signed now and now I will go back for six months on loan to play some games and gain more experience. Next season it would be normal to be loaned out, but I will start the preparations here at Cobham, and if it goes really well maybe I will stay but probably it will be a team a little level less than Chelsea but bigger than Genk. “