The Frenchman was rushed back into the team in the second leg against Lyon and suffered an injury setback which has sidelined him since.
"It's not the same situation as against Lyon, as then we forced him back in the second leg and he got injured, while this is a first leg," the coach said at a press conference prior Wednesday's game.
"I'm not going to take a risk, in order to avoid this happening again."
The former Athletic Club tactician went on to highlight the momentum of their upcoming rivals in Europe.
"Manchester United have many more solutions than set pieces," he warned.
"They are a team that are boosted from their last knockout tie and they come to these games with morale through the clouds.
"We don't set any target to go there in search of a certain result, but we know the value of scoring away from home.
"In the last knockout stage we didn't manage to score and we have to play our own game."