It is one of football’s great cliches: 2-0 is the most dangerous lead. It is never more dangerous than in an aggregate scoreline with the trailing side playing at home in the second leg. This week’s Women’s Champions League served two perfect examples in London.

Chelsea staged a big first-half comeback to march into the semifinals of the Women’s Champions League with a 3-0 victory over Manchester City on Thursday. Sandy Baltimore scored early in the all-England quarterfinal at Stamford Bridge before Nathalie Björn and Mayra Ramírez netted in a five-minute span to overturn a 2-0 deficit from the first leg and set up a last-four matchup against defending champion Barcelona.