Ahead of the second leg of their Copa del Rey fixture with Valencia, Barcelona midfielder Javier Mascherano knows that the contest is far from over.

Despite the Catalan side having an away goal advantage going into the match, the Argentinian told fcbarcelona.com that the unpredictability of cup ties is something he keeps on his mind.

"We know it'll be a difficult game and that we can't depend on the result we got at Mestalla. In the cup you can score at any time and a tie that looks won can suddenly change.” he said.

With both teams level on aggregate, Mascherano shared that the Barcelona dressing room is in a wary mood.

"People are a lot more cautious [than they were before the second leg against Real Madrid], everybody was sure we had already qualified ... We knew that Madrid would fight, would throw everything at us," the midfielder said.

"And the same will happen with Valencia, who want to reach the final as much as we do ... We are going to have to maintain the same attitude."

Mascherano also spoke about remaining focused on their league campaign, as the Los Cules fight to close in on the seven point lead currently held by Real Madrid.

"If Madrid win everything they have to win, we'll applaud them and congratulate them as a fair champion." the Argentinian stated.

"We have to do our job, and then just hope that they drop points along the way. That will be revealed at the end of the season. We can't just think it's all over ... But seven points is a big difference, so there is no room for error."

Valencia travel to the Camp Nou on Wednesday night to take on Barcelona in the second-leg of their Copa del Rey semi-final.