Former Barcelona defender Carles Puyol fears Chelsea could try and copy their 2012 blueprint for winning at the Nou Camp to again knock his former team out of the Champions League.
Barca host Antonio Conte's Blues on Wednesday night in the second leg of their last-16 tie, having scored a crucial away goal in a 1-1 draw at Stamford Bridge three weeks earlier.
However Puyol, who won the competition three times, is mindful that Barca were also in charge of their two-legged contest six years ago only to be stunned by a 10-man Chelsea side who won 3-2 on aggregate.
Trailing 1-0 from the first leg, defending champions Barca went 2-0 up at the Nou Camp yet Chelsea, for whom John Terry had been sent off, fought back through goals from Ramires and substitute Fernando Torres to progress in a competition they would eventually win.
"The difference is that we lost 1-0 in London so we had to win,'' explained Puyol. "We went out to attack and were 2-0 up, after that they made it 2-1. We did all we could to score another goal but Fernando scored the second on the counter-attack and eliminated us.
"Now I think Chelsea will play a similar game: very strong in defence and look for counter-attacks. For Barcelona, the advantage they have is that with the 1-1 draw they will go through with a 0-0.
"After the first leg I think Barcelona are the favourites but you can't be sure. Chelsea have shown that they are a very organised team with clear ideas about how they want to play and players up front who are very dangerous and very quick.
"They can hurt you a lot on the counter-attack so Barcelona will have to put in a serious performance and try to score a goal because if they don't Chelsea could hurt them on the counter.''
It was Willian who caught the eye in the first leg by striking the woodwork twice before scoring, though it is Eden Hazard who Puyol views as Chelsea's "best player."
A sterling performance from the 27-year-old Belgium international on Wednesday night would certainly enhance Chelsea's qualification prospects, yet Puyol believes he cannot yet be considered in the same bracket as Barcelona's own key man Lionel Messi, or Real Madrid's Cristiano Ronaldo.
"I don't think he's at their level yet,'' Puyol added. "We are talking about incredible players. It's not just one season, they have been at the maximum level for 10 years now.
"For me, Messi is the best player in the world and in history. It's impressive what he's doing every year at an exceptionally high level, breaking records, getting better and better in more aspects of his game.
"So to compare [Hazard] with Messi or Ronaldo is difficult, but Eden Hazard is a fantastic player.
"He's a player who makes the difference and has plenty of time to grow.''