That is the opinion of pundit and former Liverpool and England captain Steven Gerrard.
Chelsea beat Atletico 2-1 at the Wanda Metropolitano thanks to a stoppage time winner from Michy Batshuayi.
Antoine Griezmann had given the hosts a half-time lead from the penalty spot but the goal came against the run of play.
Alvaro Morata brought Chelsea level after the break before Batshuayi’s late strike.
Gerrard says he has not seen the two Spanish giants trouble Atletico like Chelsea did tonight.
“That’s the key there will be bigger and tougher tests further down the line,” he said on BT Sport.
“No they don’t (get much tougher than Atletico).
“To be fair to Chelsea, that’s the first time I’ve seen this Atletico Madrid defensive unit get torn apart.
“I’ve never seen a team, even Real Madrid and Barcelona, I’ve never seen them two sides, who are the best in the world do that to an Atletico team.
“So it was some performance.”
Chelsea have won both of their Champions League games this season and sit top of Group C.
Diego Costa and Antonio Conte shake hands
You just sense that there is a degree of unfinished business around this one.
Diego Costa took selfies with female fans in the stands and continued to savour his freedom after being finally cut loose by Chelsea this week.
He would now love it if the knockout stage draw threw up the Friends (and enemies) Reunited climax that the sub-plot to this contest is crying out for.
Costa and Antonio Conte met, as expected, in the tunnel of the Wanda Metropolitano to shake hands and signal an end to their fall-out which resulted in the striker being booted out of Chelsea.
Both sides were well aware, however, that it was all PR. Everybody knows that Conte is quite simply not having Costa while the striker would love to score that goals that knock Conte’s Chelsea out of the Champions League.
If they pile the pressure on the Italian, all the better in Costa’s opinion. He’d have already made his point, that for all his antics Conte cut his nose off to spite his face by axing him so brutally.
For now the £59million bad boy was stuck in the stands, sitting on his hands while his new/old team-mates rode their luck against his former club.
There is no doubt that Chelsea have missed his class, his guile, his spite and his ability to ruffle feathers in opposition defences.
His replacement, Alvaro Morata, is the choirboy. Costa is the streetfighter. It will have rankled that Morata’s success at filling the void so quickly at Stamford Bridge has left little room for Chelsea fans to grieve over the man whose goals delivered two titles in three seasons.
There is more to it than that, though. With Morata there are no longer those heart-in-mouth moments for the Blues when their star striker gets into it with opposition defenders.
There are no longer the sly stamps, the stray arms or the late challenges that saw results overshadowed by Costa’s antics rather than his team-mates’ hard work.
With Morata is it all about the goals and the glory. Chelsea have moved on. But Costa would still love to have the last word.