The Belgium international feels it would benefit his compatriot if he were to leave the Europa League holders permanently having impressed on loan in La Liga
The 21-year-old, who joined the Blues from Genk in the summer of 2011, is on loan at Atleti for the third consecutive season and Alderweireld feels it would be in his compatriot's best interest to either join the Liga side permanently or move elsewhere.
"He is very smart and I think it would be a good choice for him to maybe stay with Atletico, or go to another club where he will be number one," Alderweireld told Sky Sports.
"He does not want to sit on the bench for eight games then play for one.
"I don't think he has a weak point and I think he can be the best keeper in the world. He is good with the ball, he is good with his feet and he is great on his line.
"I see him in training every day and I see him in games and I doubt there are any keepers better than him."
Courtois has a contract with Chelsea until June 2016.