Despite Chelsea's request, Courtois stayed with Atletico last season and won the La Liga title but felt it was the right time to return to West London in the summer to try and conquer the Premier League.
"The first two years at Atletico had gone well and, in 2013, Chelsea had wanted me back but I wasn't 100 per cent sure," Courtois told The Guardian.
"I knew a third year in Spain would maybe be a chance to do something special. We did that by winning La Liga and reaching the Champions League final.
"After that, it felt the right moment to go to Chelsea."
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