It was in the 79th minute that Franziska Kett was sent off after pulling Salma Paralluelo's hair in the first of two semi-finals. Ten minutes earlier, the 21-year-old German had equalised to make it 1-1 after a fine pass from Danish striker Pernille Harder.
Barcelona otherwise dominated much of the semi-final in Munich. Polish player Ewa Pajor gave the away team the lead in the eighth minute.
The match ended 1-1. The return leg will be played in Barcelona next Sunday. In the second semi-final, Arsenal and Lyon will meet - the first leg will be played on Sunday.
