Lewandowski scored all four goals as Dortmund thumped Real Madrid 4-1 in their UEFA Champions League semi-final first leg on Wednesday, proving yet again why the 24-year-old Polish striker is wanted by the likes of Bayern Munich and Manchester United.

But Watzke has argued he would prefer to see Lewandowski complete his contract, which expires at the end of the 2013/14 season and leave Dortmund for free, rather than sell the Polish goal-machine.

"The fact is that Robert has a contract with us till 2014," Watzke said after Dortmund's big win over Madrid.

"Unlike Mario (Gotze, who is set to join Bayern at the end of this season) he has no release clause.

"We want Robert to play next year in Dortmund, for this we will waive a transfer fee.

"But first of all we have to talk with Robert. He is one of our most important players and a great guy.

"We have a good relationship and the transfer fee does not matter. I want him to stay, and in my life a lot of my wishes came true."

Meanwhile, Lewandowski argued his four-goal haul would mean very little if Dortmund failed to clinch a spot in the Champions League final.

Dortmund will head to Madrid next week to defend their three-goal lead and try and qualify for the final at Wembley on May 25.

"Iโ€™m happy to have scored four goals but obviously the big picture is reaching the final and thatโ€™s the only thing that counts," Lewandowski said.

"Real played well in the first half but we had things under control in the second half.

"We are very satisfied."