Since 1955, the away side has won the first leg of a knockout tie in the European Cup/Champions League on 319 occasions.
Just eight times has that team subsequently failed to progress from the tie.
SAARBRUCKEN vs AC Milan – European Cup first round, November 1955
First leg: AC Milan 3 Saarbrucken 4
Second leg: Saarbrucken 1 AC Milan 4
Aggregate: 7-5 to AC Milan
BENFICA vs Ajax – European Cup quarter-final, February 1969
First leg: Ajax 1 Benfica 3
Second leg: Benfica 1 Ajax 3
Tie-breaker in Paris: Ajax 3 Benfica 0
DYNAMO BERLIN vs Nottingham Forest – European Cup quarter-final, March 1980
First leg: Nottingham Forest 0 Dynamo Berlin 1
Second leg: Dynamo Berlin 1 Nottingham Forest 3
Aggregate: 3-2 to Nottingham Forest
PANATHINAIKOS vs Ajax – Champions League semi-final, April 1996
First leg: Ajax 0 Panathinaikos 1
Second leg: Panathinaikos 0 Ajax 3
Aggregate: 3-1 to Ajax
BAYERN MUNICH vs Inter Milan – Champions League last-16, February 2011
First leg: Inter Milan 0 Bayern Munich 1
Second leg: Bayern Munich 2 Inter Milan 3
Aggregate: 3-3; Inter won on away goals
PARIS SAINT-GERMAIN vs Manchester United – Champions League last-16, February 2019
First leg: Manchester United 0 Paris Saint-Germain 2
Second leg: Paris Saint-Germain 1 Manchester United 3
Aggregate: 3-3; Man United won on away goals
REAL MADRID vs Ajax – Champions League last-16, February 2019
First leg: Ajax 1 Real Madrid 2
Second leg: Real Madrid 1 Ajax 4
Aggregate: 5-3 to Ajax
AJAX vs Tottenham Hotspur – Champions League semi-final, April 2019
First leg: Tottenham 0 Ajax 1
Second leg: Ajax 2 Tottenham 3
Aggregate: 3-3; Tottenham won on away goals