Cape Town - Thibaut
Courtois is expected to be fit to face Tottenham Hotspur next weekend
despite leaving the Belgium squad with a muscular injury.
The Chelsea goalkeeper linked up with his international teammates ahead of their friendly with Saudi Arabia on Tuesday.
He suffered a problem following the Champions League clash with Barcelona two weeks ago, but was hopeful of earning his 56th cap for his country.
Belgium Coach Roberto Martinez explained that the former Genk shot-stopper was assessed and sent back to England for further treatment, leaving Liverpool goalkeeper Simon Mignolet to take his place.
"Thibaut Courtois, from a coaching perspective, will not be fit for Tuesday but could be okay to play at the weekend [against Tottenham] for his club. For Tuesday it is too early and a risk," he said.
"I think it's a great opportunity for Simon [Mignolet] to have back-to-back international fixtures.
"We are not going to take any chances with anyone. The medical team felt he [Courtois] would not be 100% for Tuesday."