Frank Lampard was the first to point it out and what he noticed will resonate with Jose Mourinho as the Chelsea manager prepares his team for the Nou Camp on 7 March and their greatest single test since he took over.
"Barcelona seem to be a different team to last year," the England midfielder said, "some long balls, some pushing up and not so much football until the last 20 minutes." Tighter, meaner and more disciplined: they have learned some of Chelsea's favourite tricks.
It is a theory that begs a much more serious question therefore of Mourinho's team: the problem of how they will beat - by two goals - the most exciting attacking football team on earth now that the same team has learned how to defend a lead?
The brief will be one of the most challenging that Mourinho has ever taken: he will have to commit his team to attack while hoping at the same time to contain the attacking force of Ronaldinho, Lionel Messi and Samuel Eto'o.
"This result throws up different questions: do Barcelona play their attacking, flowing football and kill the game off, or do they try and sit on the result?" Lampard said. "There's no pressure on us as we're 2-1 down and can go there with different ideas to if we were 1-0 up."
No pressure, apart from the pressure of having to beat Barcelona at the Nou Camp, a feat only Real Betis have achieved this season in August in the second leg of the Spanish equivalent of the Community Shield - and they lost the tie on aggregate. It asks a fundamental question of the squad that Mourinho has assembled at Stamford Bridge - whether it has a match-winner among its ranks, an individual who can contribute something new against a Barcelona team that seems to be re-inventing football on its own.
In short, whether Chelsea have anyone capable of what Thierry Henry achieved at the Bernabeu this week. That man might yet be Lampard who promised that his team would "give it a right good go" although it feels more like a job for a striker.
"We all know it's a hard place to go, but there's belief in this team," Lampard said. "We played 10 against 11 for 60 minutes, and we play 11 against 11 over there. The game's not over."
There is a small piece of history on Chelsea's side, as Eidur Gudjohnsen pointed out when he was asked about the daunting requirement of scoring twice away in the Champions' League. "We did it at Arsenal two years ago [in the quarter-final second leg]," he said. However, last time Chelsea visited the Nou Camp the most dangerous striker on the night was the substitute Maxi Lopez - and he now rates so low in Frank Rijkaard's estimations that he has not played once this season.
Where else, apart from his strikers, can Mourinho hope for a performance that breaks the hearts of the Nou Camp? Once he may have counted upon Arjen Robben who, in the chaos that followed Asier Del Horno's red card on Wednesday night, was chosen ahead of Joe Cole as the winger who should stay on. Until then the Dutchman had only threatened to unleash himself upon Barcelona and it was obvious from the stressful conversations he snatched with the beleaguered Del Horno in the moments leading up to the red card that Robben was nervous of straying too far out of position.
The problem with Robben is one that is widely acknowledged in private within Chelsea. That this formidable winger is keeping himself fit and fresh for what lies beyond the Champions' League final on 17 May and awaits in Germany in June and July. This is one Dutchman, according to sources at Chelsea, who takes the cause of his national team first and his club second and will not risk his precious fitness if it means missing out on the World Cup finals.
There was no comparison between Robben and the 18-year-old Messi, who was the undisputed king of the wing that both players shared on Wednesday night. Messi was a teen prodigy just like Robben, brought from Rosario in Argentina at the age of 13 and given specialist medical treatment to encourage him to grow from a slight child into the durable winger who ransacked Chelsea's defence. He also grew up close to football aristocracy: his family lived on the same street as veteran Argentina defender Nestor Sensini.
"You can't hide the disappointment, but we've got a belief and strength in our team that we've been in difficult situations before and dug ourselves out of them," Lampard said. "We by no means think it's over. We're disappointed but it's not over, we'll concentrate on the league for a couple of games and go there and try to turn it round."
Now, more than ever, Mourinho's reluctance - or his failure - to recruit one of world football's top tier of attacking players seems to be the biggest obstacle to Chelsea turning this tie around. Messi was the difference in the first leg and, in Eto'o and Ronaldinho, Barcelona have two more from that very select group of match-winners. The difference is that even with all this remarkable attacking talent, Barcelona do not even have to win on 7 March. That requirement falls upon Chelsea.Reuse content