A brilliant cup tie that swung one way and then the other, was finally decided by a stunning free kick from Man Utd's Bruno Fernandes with 12 minutes remaining.
Liverpool had taken the initiative after 18 minutes when Salah, put through by Firmino chipped the keeper to put the Merseyside side 1-0 up. Greenwood equalised with a first time effort after a stunning crossfield ball from Rashford, leaving the teams to go into half time level pegging. Rashford, put through by Greenwood returning the favour just after the restart, slotted home after 48 minutes, but Salah with his second after a defensive error, made it 2-2. Both teams pushed for a winner but when Cavani was upended by Firmino on the edge of the box on 78 minute, Fernandes stepped up to deliciously curl in the winner.
Man Utd are at home in the 5th round where they will entertain Premiership West Ham...