Borussia Dortmund manager Jurgen Klopp is confident of retaining striker Robert Lewandowski beyond the January transfer window amid interest from Manchester United.

The Bundesliga champions have reached the Champions league knock-out phase for the first time for 14 years, topping Group D ahead of Real Madrid, Ajax and Manchester City.

The form of Lewandowski, alongside Marco Reus and Mario Gotze, and been vital in Dortmund's progress to the knock-out phase and given the reported interest from United, Klopp says he isn't worried by the speculation.

Robert Lewandowski
Lewandowski has scored nine league goals for Dortmund.

"I've no idea (about this)," Klopp said. "I'm not afraid he is going to be leaving us.

"Manchester United is one of many clubs that are going to be showing an interest in him. But the fact remains the contract is with us.

"The time when there were big, rich English clubs coming to lure German players away - thank God those times are over. I'm not afraid I'll be losing him and in the second half of the season he'll be with us."

With four strikers in Wayne Rooney, Javier Hernandez, Danny Welbeck and Robin van Persie in their ranks, United are unlikely to splash out on a striker in the January window, a ploy which is seldom used by manager Sir Alex Ferguson.

The Old Trafford club signed Paul Scholes in the January window last season and aren't expected to busy in the New Year, unlike many of their rivals.

Dortmund face a dead rubber in the Champions League on Tuesday against Manchester City on Tuesday, with their passage as group winners already assured, while the Premier League champions only have the Europa League to play for.

Despite being nine points off the pace domestically, Klopp is under no illusions whether to take the game seriously.

"This is a Champions League game," Klopp added.

"When a team is through, there is sometimes a temptation to rest players but that is not for us. We are going to play with a good team.

"It will be a high-tempo game and we have got to try to put a fresh team on the pitch, but obviously there will be changes."