Thomas Tuchel hailed N’Golo Kante after the midfielder helped turned the game in Chelsea’s favour at Tottenham.
The Blues won 3-0 against their London rivals, who caused them problems in a goalless first half.
Tuchel responded by replacing Mason Mount with Kante at half-time – and the change made a massive difference.
Chelsea were two up within 12 minutes of the restart, with Thiago Silva heading them in front before Kante’s shot deflected in off Spurs’ Eric Dier.
Antonio Rudiger added an injury-time third for the visitors.
“I had the feeling that we forgot to bring the right attitude and energy to this game,” Chelsea boss Tuchel said.
“We allowed too many chances, had easy-ball losses, not enough ball possession and every 50-50 duel was going against us.
“This had to change and if you have N’Golo on the bench and you want to step up these patterns of the game then it’s the best player to bring because he’s unique and he can change any momentum.
“If you have N’Golo you have something that everybody is looking for. You have everything you need in midfield; work-rate, intensity, ball wins, skilful play with the ball and without the ball.
“I see this every day in training and it’s hard to believe how good he is. He’s a unique guy. He’s fantastic.”
The result put Chelsea joint top of the Premier League, setting them up nicely for a huge game away to champions and title rivals Manchester City next weekend.
Before that, Tuchel’s side will face Aston Villa in the Carabao Cup.
He will make changes for the third-round tie but does not expect to be able to include Christian Pulisic, who is still recovering from an ankle injury.
Tuchel explained: “I think for Christian the game against Aston Villa is maybe a bit too close.
“I hope I’m wrong, but that is my impression. It would be super-nice for us to have him, but for me it’s a bit doubtful.”