Dortmund coach Sahin believes it's unfair to underestimate Celtic

The last time Celtic made it past the group stage in the competition was in 2013, but they have made an impressive start to this season, winning all nine games across all competitions, including a 5-1 win over Slovan Bratislava in the Champions League.

"We're talking about a team that hasn't lost a lot of games, that hasn't conceded in their own league, that was very dominant in their first Champions League game," Sahin told a press conference ahead of Tuesday's game.

"I'm looking forward to it and to call them outsiders, that would be unfair to Celtic.

"What can I say about Celtic, a prestigious club with amazing talent in the club, a fantastic coach."

Sahin knows all about Celtic's manager, after his time under Rodgers as a player when he had a loan spell at Liverpool in 2012.

Although he only made seven league appearances for the club before his loan came to a premature end and he moved to Dortmund for the second half of that season, Sahin says Rodgers was an influence on his own coaching career.

"I'm looking forward to it. We had a short time together, a lot of talks before the transfer and also during my spell there," Sahin said.

"I really enjoyed it. I found his training sessions and his idea of football very, very interesting. I also wrote down a lot for my coaching career back then.

"Tomorrow I think we'll see each other again after 12 years and I'm looking forward to the duel."

Defender Julian Ryerson and midfielder Jamie Gittens were both taken off during Friday's league win over VfL Bochum, but Sahin said they will be available for the game with Celtic, while Giovanni Reyna is still out with a groin strain.