Both Champions League quarter-final ties played on Tuesday ended in 1-1 draws as Barcelona and Atletico Madrid and Manchester United and Bayern Munich could not be separated.
Neymar cancelled out a stunning opening goal by Diego Ribas to ensure it ended all square between Barcelona and Atleti at the Nou Camp, with everything to play for in the second leg next week at the Calderon.
Brazilian forward Ribas came on to replace Atletico's talisman Diego Costa after half an hour and unleashed an unstoppable drive from 30 yards to put the visitors ahead 11 minutes into the second half.
But compatriot Neymar finished off a fine pass by Andres Iniesta to level the score 15 minutes later and set up the fourth successive draw in the meetings between the two teams this season.
At Old Trafford, United rode a wave of possession against Bayern to take the lead through captain Nemanja Vidic's header.
Bayern responded like the defending champions they are, though, through Bastian Schweinsteiger, who later saw red for a second yellow card.