The ex-Napoli boss had a falling out at the Italian club, opening the door for him to move to Chelsea.
The Belgian global - enjoying the final day of a post-World Cup break - was a special guest of KRC Genk during their second First Division A meeting of the new season against Sint-Truiden, which finished 1-1.
This may be a club that has managed win trophies despite their lack of managerial stability during the Abramovich era, yet the blackened clouds of uncertainly gathering at Chelsea appear to be the most threatening yet with just four days left of the summer transfer window.
Speaking at a press conference the 59-year-old master tactician was asked about Courtois and if he will remain at the club, to which he replied, "Courtois? If he wants to be number one, he needs to be playing in the Premier League".
Woods-Mickelson showdown set for Thanksgiving
The duo have been rivals for much of their careers, with Mickelson a long-time number two to Woods' domination as world No.1. Woods is a vice captain for 2018 captain Jim Furyk and is fighting for one of the four at-large picks.
Willian is another Chelsea player linked with a move, with Manchester United, Barcelona and Real reportedly courting the Brazil playmaker but Luiz dismissed the idea of his lifelong friend leaving. "Everybody has the opportunity, you just have to show him character, physical quality, technical quality, so since the first day I'm trying to do that". But I have my head here and I intend to continue in the club unless the club wants to sell me.
This was an easy decision for Chelsea as they knew they would be parting with Antonio Conte come seasons end. So we have everything to improve and keep working.
"We have the idea to be in control of the match but today we were not in control of the match".