Dortmund run the risk of losing Guerreiro on a free transfer if they cannot sign him to fresh terms and allegedly offered him a three-year deal worth €5million a year.
But Dortmund sporting director Michael Zorc gave little away on the progress of their discussions in a press conference ahead of Friday's Bundesliga clash with Cologne.
"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."
Dortmund’s opening-day win came despite falling behind to a goal from Augsburg’s Florian Niederlechner in the first minute. Two goals from Paco Alcacer and one each for Jadon Sancho, Marco Reus and substitute Julian Brandt completed a comfortable victory for last season's Bundesliga runners-up.
Guerreiro missed the fixture with a hamstring injury that looks set to keep him out of action until the end of the month. The 25-year-old made 32 appearances for BVB last season as the club were narrowly pipped to the Bundesliga title by Bayern Munich.
Friday’s opponents Cologne suffered a 2-1 away defeat at Wolfsburg in their opening match.