Fuming Blues boss Antonio Conte is now poised to veto the club’s participation in a basketball promotion which resulted in his Belgium international no.1 picking up an ankle injury.
The setback ruled Courtois out of Sunday’s 2-0 defeat at Manchester United, a result that blew the title race wide open.
Marcos Alonso was also understood to have been involved in the basketball shoot at Chelsea’s Cobham HQ. He too limped out of the warm-up ahead of the United game and did not return.
He too is on course to miss Sunday’s Wembley showdown with Spurs.
It is a nightmare scenario for the Blues who have seen their seven point lead over Mauricio Pochettino’s red-hot side reduced to just four points at the weekend.
Other players believed to have taken part in last week’s shoot include Nathan Ake, Nemanja Matic and reserve keeper Asmir Begovic, now set to keep his place after stepping in for Courtois at Old Trafford.
The players were doing in a number of drills including tricks, half-court challenges and competing in a mini-game.
It is claimed Courtois – who posted pictures of himself with Philadelphia 76ers star Joel Hans Embiid to Instagram – “got a bit carried away” as he leapt to receive a ball, twisted his ankle and landed awkwardly.
Chelsea are understood to have then scrapped plans for more of their players to get involved after Courtois sustained his injury last week.
After being in total control of the title race, they have now lost two of their last four Premier League games and face Southampton at home next Tuesday night.