Now in charge of Brighton, Poyet is convinced of who was responsible for taking the club into the elite of Europe.
He told chelseafc.com: "Everything started changing when Chelsea won the 1997 FA Cup, that's when the team started getting better, more entertaining and winning important games.
"We then won the Cup Winners' Cup, the Super Cup and the club was still getting better.
"At that time everyone was expecting the side to win the Premier League or Champions League. But this is not easy. The club needed something to happen and that came with the arrival of Jose Mourinho.
"Obviously Roman Abramovich definitely helped, no doubt, but Claudio Ranieri wasn't able to win a trophy with the money from Abramovich.
"Then Mourinho arrived and the club went boom, to another level! That changed Chelsea completely."