The Belgian goalkeeper is in the middle of his third loan spell in the Spanish capital and reinforced his status as one of the standout shot-stoppers in Europe with another fine display against Barcelona on Tuesday night.
Atletico are keen to secure a permanent deal for the 21-year-old – who has been mooted as a makeweight in a potential swap as the Blues chase striker Diego Costa – while the English club see him as the long-term successor to Petr Cech.
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"Next week it will become clear where I'm playing next season," he told Sporza.
"It's certain that it will be Chelsea or Atletico and no other club. I can't say much more about it but, in the next weeks, there will be official news."
Courtois played an influential role in Atleti's 1-1 draw against Barcelona at Camp Nou as Diego Simeone's men claimed an away goal and narrow advantage in the first-leg of their Champions League quarter-final.
The Belgian remarked: "It was a really tough match. Last Saturday we had a very tough game against [Athletic] Bilbao so this was pretty heavy for us. We had to defend a lot and run behind the Barca players but we scored an away goal so I think that's really positive.
"I had some important saves so I'm really happy with that. I couldn't see Xavi's shot at first so I had to give everything to get to it. I knew that [Lionel] Messi would shoot his free kick over the wall so I had to have that one."