Courtois made a string of saves to help Atletico to a 3-1 win at Stamford Bridge that gives them a place in the final against city rivals Real Madrid, while also cementing his reputation as one of the world's best young goalkeepers. (Agencies)
With the match finely balanced at 1-1, Courtois produced an instinctive stop to keep out a powerful header from Chelsea captain John Terry shortly after halftime.
After Atletico took the lead, the keeper continued to stand firm, denying the Blues a way back into the game.
"I thought he was outstanding," said veteran Chelsea goalkeeper Mark Schwarzer, who at 41 is almost twice the age of the 21-year-old Courtois.
"He had a great game tonight. If we'd been a bit lucky and he'd been a bit unlucky we could have got back in the game and there could have been a few more nervy moments towards the end for them. It wasn't the case."
Courtois's Chelsea future remains unclear. The keeper is in his third season on loan in Madrid and the two clubs have yet to say whether he will return to London next term, after he has played for Belgium at the World Cup in Brazil.
Chelsea's first-choice keeper Petr Cech missed Wednesday's match after injuring his shoulder in the first leg last week in Madrid and would face stiff competition from Courtois should he return.
"It's a very, very tough decision and I am glad I am not the one making it," Schwarzer said.
"They are both world class goalkeepers and I wouldn't say that they are at different ends of their careers because Petr still has a long way to go with his career."
Courtois made a string of saves to help Atletico to a 3-1 win at Stamford Bridge that gives them a place in the final against city rivals Real Madrid, while also cementing his reputation as one of the world's best young goalkeepers.