Los Leones are 14th in the La Liga table, six points clear of the relegation zone, and the Argentinian claimed the impact would be purely psychological, win or lose.
"Whatever happens, it will be exaggerated," he said. "If we get points the situation is softened and if we lose, it is aggravated, but numerically, we are in the same situation.
"Whether we win or lose, it won't change the situation we are trying to get out of. The feeling you get after a win makes you much more optimistic, while a defeat does the opposite."
Athletic face a Valencia side who were knocked out of the Champions League by Paris St Germain on Wednesday, but Bielsa believes they will not be affected by the result when they come to San Mames.
He said: "The result against PSG is totally irrelevant. If they had won, they would have come here stimulated and relaxed, if they'd lost they would come here down in the dumps and looking for revenge and to reclaim their place in next year's competition.
"Either result gives them reasons to want to play better. But in any case, victorious or not, they are a team with quality players and a top class side."
Midfielder Ander Herrera will miss the tie due to suspension and Bielsa said there was not one player who could fill in for the former Real Zaragoza player, and several players would have to share the tasks he normally carries out for the team.
"We have to try and get more than one player to do the different things he normally does," he said.
"[Ander] Iturraspe, [Oscar] De Marcos, [Iker] Muniain will have to try and pool their own characteristics so that his absence is noted as little as possible."
Valencia midfielder Sergio Canales said that while his team are disappointed with exiting the Champions League, they are now putting all their efforts into reaching fourth place in the table so they can compete in Europe's elite competition.
He told reporters: "We are very proud of ourselves, we tried to get through but it wasn't meant to be, and now we have to go for fourth place. The coach and the players are happy with our performances and we know what we have to do."
Andres Guardado is suspended for Valencia, while Joao Pereira is a doubt due to a hamstring injury. Roberto Soldado, who missed training on Thursday with flu, is also a doubt.