Sporting director Michael Zorc unable to give any clues as to whether the defender will be staying at the club for the long term
Raphael Guerreiro remains in talks with Borussia Dortmund with the Bundesliga club having reportedly offered the defender another contract extension.
"We are still in talks," Zorc said. "I cannot give you any indication right now.
"We have to wait, we're not the only ones who decide."
On possible changes to the squad during what is left of the transfer window, he added: "It's just over a week's time. There may be something else happening, but I cannot promise that."
Mario Gotze came off the bench in Dortmund's 5-1 demolition of Augsburg to start the league campaign.
Asked about the World Cup winner, coach Lucien Favre said: "One year ago he was in a similar situation. He has already played 20 minutes against Augsburg. We have some competition, and Thorgan Hazard and Jacob Bruun Larsen can play in the attack. Mario can also play behind the striker.
"It will be a difficult game. We have seen Cologne several times. They have found a good spine and quality in the team.
"They press very hard and with intensity. We have to be prepared for everything."