Lionel Messi has issued a rallying cry for Barcelona to step up their game against Real Madrid after they were forced to come from behind to beat Sevilla 2-1 on Saturday night.The Blaugrana needed second-half goals from David Villa and the Argentine forward to prevent another disappointing result this week, following their 2-0 loss against AC Milan on Wednesday."We knew it would be a difficult game, more so after the result against Milan. But we won, and that's the main thing," Messi was reported as saying after the Camp Nou victory."I feel good, and like to play. Now we must play like we always do in the cup game against Madrid. We won't be able to count on a 0-0 draw."When asked about reports in the Spanish media which alleged that the 25-year-old insulted los Blancos assistant Aitor Karanka after their first-leg stalemate in Madrid, Messi declared his lack of concern in such things."Knowing where they come from, I don't care too much about it," he added, abruptly.Barca stand-in coach Jordi Roura insisted that Villa remains instrumental to the club's project, with the Spain international having initiated the turnaround after Alberto Botia put the visitors into a shock lead on the stroke of half-time."We've always said that Villa is a key player for us," Roura told reporters. "He consistently shows it. He scores easily and that's very important."At half-time, I asked the players to stay calm and not to hurry. Alexis [Sanchez] got a serious knock, so [Cristian] Tello came on earlier and added a lot, creating space for others."Of course we're worried about conceding goals. We try to improve that, just like we try to improve other things."