Borussia Dortmund striker Robert Lewandowski is set to join German side Bayern munich in june after a pre-contract agreement the 25-year-old poland international has agreed terms on a five-year deal and will arrive at bayern on a free transfer when his contract expires. Lewandowski is the second key Dortmund player within a year to announce a move to bayern, after playmaker Mario Gotze agreed to transfer to the allianz arena last april. Lewandowski has helped Dortmund to the 2010-11 and 2011-12 bundesliga titles, plus the 2012 dfb-pokal cup, since signing from lech poznan in 2010. He played a starring role in their run to an eventful champions league final defeat to bayern last season, memorably scoring four goals in the semi-final first leg against Real Madrid. Jurgen klopp's side have struggled this term, however, and sit 12 points behind leaders bayern in fourth.