Former Barcelona captain Carles Puyol has warned Ernesto Valverde's side not to take Chelsea lightly when they face the Premier League side in the second leg of the Champions League round of 16 on March 14.
Barcelona hold a slight edge in the tie after Lionel Messi cancelled out Willian's opener in the first leg at Stamford Bridge. A goalless draw would be enough for the Catalan giants to progress to the quarter-final stage, courtesy of the away goals rule.
Chelsea have struggled to maintain the Premier League title-winning standard they set last season, with Antonio Conte's side currently in fifth place on the league table.
But Puyol pointed to how an unfancied Chelsea team under Roberto Di Matteo knocked out Barcelona in the semi-final stage in 2012 as a cautionary tale against underestimating the Blues.
"The difference is that we lost 1-0 in London so we had to win,'' the former centre-back recounted to PA Sport.
"We went out to attack and were 2-0 up [in the second leg], after that they made it 2-1. We did all we could to score another goal but Fernando [Torres] 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," Puyol added.
"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.''
Barcelona will hand a late fitness test to Andres Iniesta, who is nursing a hamstring injury, before the Nou Camp showdown against Chelsea.
Antonio Rudiger is available for the visitors after he was rested for Chelsea's victory over Crystal Palace at the weekend.