Manuel Pellegrini’s side took a 2-2 draw away from Camp Nou in the first leg and Roura is well aware of the importance of winning the game on the back of a defeat to Real Sociedad in La Liga on Saturday.
“This is the first must-win game we have had this season and we will travel out there with that intention,” Roura told reporters.
“I do not think that they will need a special message from me beforehand. I have no doubt that we will give everything we can to progress.”
The stand-in boss also admitted that he is conscious of the possibility of a cup upset and said that his players will be determined to ensure that does not happen.
“Everyone is aware of the importance of the shock and we will put the intensity into the game that it deserves. The team always wants to play and we all know the importance of having a good attitude," he continued.
“They've had the same amount of days to rest as us and it's a huge game for them too, the chance to get to the semi-finals. Each game has its own characteristics. This one will be very complicated. They have many things in their favour, the fans, the score from the first leg and that this game will be played at their ground.”
However, Roura has dismissed the notion the game has come at the wrong time for Barca, who have not won in their last two games, and thinks the team will have enough to progress to the semi-final.
“The first half in San Sebastian [in the first leg] was first class, as it was against Malaga [last week]. Then both games became difficult for us. The game has not come at a bad time for us," he insisted.
“Right now, looking at how the players are doing and the effort they are putting in, I think we'll qualify, but this is football, and anything can happen.”