Cesc Fabregas believes Barcelona's Champions League games against AC Milan will be a tough test and they will have to play at the top of their game to progress.
Barca face Milan at the San Siro on Wednesday in the the first leg of their last-16 tie, with the return game at the Camp Nou on March 12.
The midfielder, who was speaking at a sponsors' event which involved him learning how to make sushi, said the Serie A club's impressive current squad and European pedigree make them formidable opponents.
"It will be very difficult," he said. "We will need to be at our best to beat them. The match against Milan is key because we want to go to Wembley. We believe that they will be a very difficult rival because of the players they have and because of their history. If we are not at 100% we will not go through to the next round."
Barca's busy schedule over the next few weeks also includes the Copa del Rey semi-final at home to Real Madrid on Tuesday, February 26 and another Clasico at the Estadio Santiago Bernabeu in La Liga on Saturday, March 2.
Fabregas said the team's current outstanding form would help them through the run of demanding fixtures which will go a long way to determining their season.
"The next two weeks are extremely important," he said. "We must keep going with the same intensity, and be very focused."
The World Cup and double European Championship winner, who rejoined the Catalan club from Arsenal in August 2011 in a deal worth around €40 million, said lifting the Champions League trophy with his local club was now the most important aspiration of his career.
"I am very eager to win the Champions League," he said. "It is the title which most excites me. To win it with Barca is my biggest ambition as a footballer."
Fabregas played in the 2006 Champions League final when Arsenal were beaten 2-1 by Barcelona.