Dejan Lovren scored a heart-stopping stoppage-time header as Liverpool completed an astonishing comeback to beat Borussia Dortmund 4-3 on Thursday and reach the Europa League semi-finals. Held 1-1 in last week's first leg at the Westfalenstadion, Dortmund scored twice in nine minutes through Henrikh Mkhitaryan and Pierre-Emerick Aubameyang to take a firm grip on the tie. After Divock Origi had given Liverpool a foothold, Marco Reus struck again for the visitors, but goals from Philippe Coutinho and Mamadou Sakho levelled the tie before Lovren headed home in the 91st minute to give former Dortmund coach Jurgen Klopp the biggest win of his Anfield tenure.