Robert Lewandowksi netted all four goals as Borussia Dortmund beat Real Madrid 4-1 in their Champions League semi-final first-leg clash Wednesday at the Westfalenstadion. Having seen Bayern Munich demolish Barcelona 4-0 a day earlier in the other semi-final in Munich, Polish international Lewandowski's goalscoring heroics mean it is now odds on that next month's final in Wembley will be an all German affair. Mario Goetze showed why newly-crowned German champions Bayern spent 37 million euros (48 million dollars) for his services from next season with a superb cross on eight minutes for Lewandowski to steer home his first from close range. Cristiano Ronaldo pulled one back for the visitors just before the break after a dreadful error by Dortmund defender Mats Hummels but Lewandowski turned the tie firmly back in the German side's favour with two more goals within 10 minutes of the restart. Lewandowski netted Dortmund's fourth on 66 minutes from the penalty spot after Marco Reus was adjudged to have been pushed in the area by Xabi Alonso to give Juergen Klopp's side a comfortable three-goal cushion going into next week's return leg at the Bernabeu.