Paris Saint-Germain manager says his side face an "extremely difficult" test if they are to overcome a deficit in the second leg of their Champions League quarterfinal on Tuesday.
Barcelona ran out to a 3-1 win last week at the Parc des Princes, and Blanc acknowledged that it will be even more difficult to keep the Spanish giants from scoring at the Camp Nou.
"I am pretty realistic... Obviously I think we can do it, but it will be extremely difficult," Blanc said in a news conference. "We need to score goals and I truly believe we will have opportunities to do that. The biggest difficulty will be to avoid conceding.
"We have nothing to lose and we want to show we can play better than we did in the first leg."
Blanc said the majority of PSG's chances to trim their deficit will be on the counter-attack.
"They will have the ball, and we will look to counter, so we have to score, score a lot without conceding," Blanc said. "Barcelona will be looking to confirm their result from the first leg, at home, in front of their fans. It will be tough, but we must believe we can do it."
PSG will be without captain Thiago Silva, who was forced off after 21 minutes of the first leg with a thigh injury, meaning David Luiz will again play in the centre of defence after struggling in the first leg.
Laurent Blanc has a selection dilemma for Tuesday's match in Spain, with Serge Aurier suspended and Thiago Motta also out injured, but he will welcome back Marco Verratti and Zlatan Ibrahimovic from suspensions.
Ibrahimovic, who is still serving a three-match ban in Ligue 1 for his comments toward officials, returns following his one-game Champions League ban for a red card in the round of 16 against Chelsea.
"We saw in the first leg, just how important Zlatan is," Blanc said. "Despite his suspension, Ibra has been training every day and is in good form. We have a number of objectives and he brings a lot to the team."
Midfielder Javier Pastore agreed with his manager that PSG face an uphill battle in the second leg.
"It will be a very difficult match. We have nothing to lose," he said. "The first leg was a very bad result for us, but we get two important players back that can help the team a lot.
"We will try to win with them. It will be tough, but we believe. That's what we're working towards. Sometimes football can provide a surprise."