Sergio Gonzalez's Espanyol have suffered three straight losses in all competitions, the latest defeat a 2-1 loss at home to Valencia.
They remain mid-table in La Liga, but the run of losses is worrying ahead of a trip to San Mames.
Speaking after the loss to Valencia, Gonzalez admitted a lack of confidence may be affecting his team - but he believes they deserved more from that clash.
"We are professionals, we have to move on. It won't affect us. The football we played isn't why we didn't win," he was quoted as saying by Marca.
"There's an argument the team doesn’t have confidence. We lost with our heads high and we’re going to [Athletic Bilbao] to give our everything."
But Ernesto Valverde's men had a four-match unbeaten run ended on Sunday, going down 5-2 to Barcelona.
A good result at home is crucial to Bilbao's chances of reaching the final, and they need to take control early against an Espanyol side lacking confidence.
