"For me, Courtois is one of the best", he said on Sky Sports' Premier League launch show.
"He has already demonstrated fantastic quality and consistency and will be a big part of any success Chelsea have in the coming years", Chelsea director Marina Granovskaia said.
The Blues have had a busy couple of days in the transfer window, with Chelsea signing Kepa in a world-record deal yesterday.
Courtois, who is now into the final 12 months of his contract at Stamford Bridge, wants to move to the Spanish giants.
He had been set to join Real Madrid in January for a fee of just £17.5m - even passing a medical at the Santiago Bernabeu.
Seen as a panic purchase by some, Chelsea have addressed a position of need and have now paved the way for Golden Glove victor Thibaut Courtois to finally make his dream move to Real Madrid.
Newcastle legend Shearer has sympathy for Man Utd boss Mourinho
It's been a pretty gloomy pre-season for Jose Mourinho and Manchester United . The Fiver: sign up and get our daily football email .
The Blues No 1 got his wish with Real expected to announce their new signing this afternoon.
"I'm really looking forward to starting to work with [Sarri]", Kepa told the official Chelsea app The 5th Stand.
But the youngster has impressed when given the opportunity for both club and country and seems to be a good fit for a three-man Chelsea midfield alongside Jorginho and N'Golo Kante.
Sarri is also getting Kovacic, who had not played much with Madrid since joining the club in 2015 and had been seeking a transfer.
The Belgium has been tipped to quit Chelsea for Real in recent weeks.
Chelsea face Huddersfield on Saturday afternoon (3pm kick-off).