The highly-rated goalkeeper, just has to sign on the dotted line, in a move that will see him stay in Belgium for another year
The youngster only has to agree personal terms with the Blues before completing a move, which is believed to have cost the English club €6 million after an earlier bid of €4m was rejected. He will remain in Belgium for the time being, before joining Chelsea at the start of the 2012-13 season.
"Thibaut must now see if he is satisfied with the agreement and the terms being offered to him," his father Thierry was quoted as saying in Belgian newspaper le Dernier Heure.
Genk's managing director, Dirk Degraen, told news agency Belga that he would not be revealing any details regarding the move before Friday evening. The agreement comes one day before the club's planned transfer embargo, which pledges that no first-choice players will depart between July 15 and August 27.
Courtois burst onto the scene a year ago when he stepped in for then first-choice goalkeeper Laszlo Koteles, who was unable to compete in European competition due to his former club not having delivered all the necessary paperwork in time. He became an ever-present figure in Francky Vercauteren's title-winning team, producing a string of stunning saves in the title decider against Standard Liege.
Earlier last month, Courtois let slip on Brussels FM that Chelsea had earmarked him as the long-term successor to Czech goalkeeper Petr Cech. He is yet to be capped at full international level but received a call-up for Belgium's recent Euro 2012 qualifier against Turkey.