BERLIN : Union Berlin came from a goal down to beat VfL Wolfsburg 2-1 in the German Cup on Tuesday and reach the quarter-finals.Union, who earlier on Tuesday spectacularly failed to sign Spain international Isco with talks collapsing in Berlin even after the player had passed his medical, fell behind after five minutes.Wolfsburg's Luca Waldschmidt drilled in for an early lead in a nightmare start for the hosts.They recovered quickly, however, and former Wolves player Robin Knoche levelled in the 12th, volleying in after a corner.Union, playing a sensational Bundesliga season and lying in second place a point behind leaders Bayern Munich, came close to scoring again with Jordan's header bouncing off the crossbar in the 27th.They eventually bagged the winner in the 79th with Kevin Behrens stabbing in from close range before their defender Niko Giesselmann was sent off with a second booking in the 87th.