Barca are hot favourites to land their fourth European Cup, with some observers even dubbing them the best club team of all time.
Chelsea may well need to defeat them if they are to realise their own Champions League dream and manager Ancelotti is adamant the Catalan giants are are not invincible.
Clash of styles: Chelsea were unlucky not to beat Barca in the 2009 semi-finals
'Barcelona now are the best team in Europe,' said the Italian, whose side will join Barca in this season's quarter-finals barring a massive shock in their last-16 second leg against FC Copenhagen.
'The performances of Barcelona at this moment are fantastic, but every game is a different story. If we have to play them, we have to try to find a solution to beat them.'
Ancelotti suggested 'strength and power' were the way to combat Barca's peerless passing game. The tactic certainly worked for European Cup holders Inter Milan last season, while Chelsea were desperately unlucky not to topple Barca a year earlier.
Arsenal tried to fight fire with fire in their last-16 clash with the Spanish champions and were brutally exposed, just as they were last term. Ancelotti was at pains to point out a meeting with Pep Guardiola's team was not a foregone conclusion, insisting his side still had plenty of work to do.
Playing with fire: Arsenal tried to beat the Nou Camp giants at their own game in this year's last-16 tie and were soundly beaten by the end
'We have to pay attention,' he said. 'Copenhagen are a good team with good organisation.'
That was certainly not the case three weeks ago, when the Danish champions looked every inch a side playing their first competitive match since a three-month winter break.
Yet, despite the quality of the opposition, the win had a galvanising effect on a Chelsea team whose season was on the brink of unravelling but who have since beaten both Manchester United and Blackpool.
Admitting the Copenhagen victory was the 'turning point' of his side's stuttering season, Ancelotti said: 'Copenhagen was an important match to move on. "It gave us confidence, optimism, not just the result.'
Pole position: Chelsea take a 2-0 lead into the second leg against Copenhagen
The second leg promises to be an emotional one for Copenhagen winger Jesper Gronkjaer, who will play at Stamford Bridge for the first time since leaving Chelsea in 2004.
The 33-year-old scored on his last two appearances at the stadium but was not banking on making it a hat-trick tomorrow. He added: 'It's going to be funny. I just had a short walk around the stadium now and saw a few people I've seen before.
'It's going to be a fantastic atmosphere tomorrow. It's going to be a walk down memory lane. I've got great memories here but now I'm playing for FC Copenhagen and I want to win here and we're going to give it a good go tomorrow.
'We know we didn't play our best game in Copenhagen but we want to keep the dream alive.'
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