Despite the disadvantage heading into the return leg, Roura is confident that the Catalan club can turn the tie on its head.
"We are confident in our own team and playing at our own stadium," said Roura. "It will be a different story in the second leg. We fully believe we can turn this around.
"This wasn't our best game. Although we had problems I think that the result is excessive.
"They found a couple of opportunities and scored from them which now makes things tricky for us."
The second leg takes place at the Camp Nou in three weeks' time.