Van Persie was a surprise addition to the Gunners' squad for the match at the Nou Camp, having previously been ruled out for the majority of March with a knee injury picked up in the Carling Cup final.
But the Netherlands international, who has ten goals in nine Premier League starts this season,will spearhead Arsenal's attack as they aim to defend a 2-1 lead in Spain - and Fabregas is elated to see him in the travelling party.
"Robin is a very important player for us, he is the perfect striker, he can do everything and understands the game very, very well," said Fabregas. "For a midfielder to have a player like him, it is fantastic because he gives you all the options that you need.
"I was very surprised [to hear he was in the squad] because this [Monday] morning we did not know anything about it. He woke up feeling great and said he wanted to try and practice. No-one wanted to cheat on anyone, it has been a surprise on the whole team.
"He was bandaging his ankle for training and said 'I am doing great and I want to try. Let's see how I feel tomorrow'. If he is fit to play, it would be very good."
Barcelona starting XI: Valdes, Alves, Busquets, Abidal, Adriano, Mascherano, Xavi, Iniesta, Messi, Pedro, Villa
Arsenal starting XI: Szczesny, Sagna, Djourou, Koscielny, Clichy, Diaby, Wilshere, Rosicky, Nasri, Fabregas, Van Persie