Of the many significant elements to this appealing Fifa Club World Cup semi-final, ranging from an exquisite Oscar back-heel to another reminder of Juan Mata's elegant enterprise, one of the most important came just before the end, bringing a negative that could prove a positive.
A consolation goal for modest Monterrey screamed a warning to Chelsea of the need to concentrate against far more substantial opposition, Corinthians, if they are to become champions of the world.
Oscar, Mata and company can win this competition on Sunday. Corinthians are good, defensively tight, highly capable on the counter, but they are not the most formidable of teams to have left the shores of Brazil.
If Chelsea are to prevail, they will need to take their chances and keep an eagle eye on the movement of the likes of Paulinho and Paolo Guerrero.
Careless concentration costs goals. Like here. Chelsea had the game won, had the comforting cushion of goals from Mata, Fernando Torres and a Darvin Chavez aberration when they, and particularly Ashley Cole, dozed off and Aldo De Nigris swooped.
An English side drilled by a former Liverpool manager should not need a lesson in the danger of a striker called Aldo.
"I'm not very happy with the goal we conceded," said Rafa Benitez, Chelsea's interim first-team coach. "When I talk about a winning mentality, always I talk about little details making the difference. They have to keep their concentration right to the end."
Until then, Chelsea excelled. A few anxiety pains stained their game in the middle of the first half. Jesus Corona had clearly come to bury Cesar Azpilicueta and the Chelsea right-back endured some worrying moments.
Otherwise, Benitez's side were largely in control. His decision to start David Luiz in midfield – roaming upfield with John Obi Mikel diligently guarding the back door – was a success.
There was much in the buccaneering work of Luiz, the passing of Oscar and the finishing of Mata to delight the curious mix of fans in the Chelsea end, where salary-men sat and celery-men stood.
Around 900 fans had travelled from England, singing about Tottenham, Leicester and Leeds, while the locals beamed benignly. There was much to smile about.
Shortly after the usual tribute to the dismissed Roberto Di Matteo, Chelsea fans celebrated taking the lead.
Oscar released Cole with a back-heeled return and the left-back was off and running like a waiter chasing a tip, delivering the ball perfectly for Mata to score. Chelsea fans were loving it.
The banners in blue indicated that their owners had journeyed from Adelaide, Melbourne, Indonesia, New York and Dorset. They certainly got good value for their air-miles, especially at the start of the second half with two goals in three minutes.
First Eden Hazard found Torres (left) , whose shot took a heavy deflection and beat Jonathan Orozco.
Torres then cut in from the left and bent the ball with the outside of his boot across to Mata. The rest was a blur of Mata's ball in, Chavez's legs in a tangle and the ball nestling in the net.
Sunday will be "a football party," according to Mata, but Chelsea must beware showing any bonhomie to Corinthians. (© Daily Telegraph, London)