Leonardo believes Paris Saint-Germain have "a great opportunity" to surprise Barcelona in Wednesday's quarter-final second leg, despite heading to the Camp Nou as underdogs.
Last week's 2-2 draw in the French capital means Barca have the edge in the tie before playing host to Carlo Ancelotti's men.
However, following Blaise Matuidi's equaliser in added time at the Parc des Princes, PSG's sporting director, 43, is confident his team can end Barcelona's record of not having lost at this stage of the competition in a decade.
"Honestly, we have to take it as a great day for us. We're in an extraordinary position," the Brazilian told media at a charity event on Sunday.
"Barcelona are 20 years into their project. Ever since Cruyff, Barcelona have played like that and they've almost achieved perfection with some incredible generations of players.
"PSG has started a great chapter in its history, but the squad only started working together 20 months ago. However, that doesn't take away the feeling that we have a great opportunity."
Though PSG's chances would be harmed should Thiago Silva, 28, fail to recover from the knee injury that kept him out of this weekend's league win over Rennes, the absence of Lionel Messi, 25, from Barca's ranks would be a significant boon.
After limping off with a thigh injury at half-time in the first leg, the Argentine has been racing to recover his fitness for Wednesday's encounter, but Ancelotti, 53, insisted it makes no difference to his team if the World Player of the Year features or not.
He said: "We mustn't focus on him. With or without him, it's the same for us. We have to concentrate on what we know how to do in the defensive and attacking sectors of the pitch."
Midfielder Matuidi, 25, who is suspended for Wednesday's game, added in L'Equipe: "He's the best player in the world, so of course it changes some things if he doesn't play. But above all we're thinking about playing our game, playing to our strengths and doing what we know best how to do. We're going there to qualify, not as tourists."