Jurgen Klopp keen to ward off Manchester United interest in Robert Lewandowski

Jurgen Klopp is desperate to keep Robert Lewandowski at Borussia Dortmund next season.

The Pole was the scourge of Real Madrid during their Champions League tie on Wednesday night, scoring all four goals in a wonderful individual display as the German side thrashed Jose Mourinho's men 4-1 in the first leg of their semi-final.

The 24-year-old is out of contract at the end of next season and has so far refused to commit to a new deal, meaning the Bundesliga side must now consider whether to cash in at the end of the season or lose him for nothing in 2014.

Speculation in Germany has suggested Bayern Munich and Manchester United are leading the race to sign Lewandowski, with the pair set to fight it out this summer.

Bayern coach Jupp Heynckes' agent even claimed this week Lewandowski had an agreement in place with the Bundesliga champions but Klopp is willing to play the waiting game.

"I don't get the feeling Robert is on the run," said Klopp to ZDF television. "We'll just have to see what happens."

Lewandowski refused to discuss his future post-match but Dortmund general manager Hans-Joachim Watzke outlined the club's determination to keep him for another 12 months even if it means seeing him eventually depart on a free transfer.

"Our wish is explicit that he stays here," he told Sky television. "We will even do without receiving a transfer fee for him - that doesn't interest us in the slightest.

"Robert's contract runs until 2014 and, unlike Mario Gotze, there is no get-out clause."

Klopp believes Poland international Lewandowski last night wrote his name into Dortmund folklore, adding: "Whenever I walk through the Borusseum (the club's museum), I always see the same old videos.

"Maybe now Robert's four goals will find a place in there, but for that to happen, we have got to build on this in the second leg."

Despite holding a handsome first-leg lead, Klopp insists his side will not sit back in next week's return at the Bernabeu.

"We are not a team who can simply defend a result," he said. "We always want to attack.

"I brought (Sebastian) Kehl and (Kevin) Grosskreutz on tonight to strengthen us defensively, and the first thing they did was in the Real Madrid penalty area. I think that says it all.

"We have played an extraordinary game against a fantastic team, but nothing has been decided yet.

"But even if we get knocked out, nobody can take this night away from us."