I have been looking for bigger comeback than PSG vs Barcelona in 2017 i.e La Remontada in which Barca beat PSG in second leg. Artmedia Bratislava vs Celtic was close as they lost 5-0 in first leg but Celtic could get only 4. I have found couple of examples but all were 4 goal
Real Madrid vs Borussia Mönchengladbach, 1985-86 UEFA Cup
Partizan Belgrade vs QPR, 1984-85 UEFA Cup
Leixões SC vs FC La Chaux-de-Fonds,1961/62 UEFA Cup
CONMEBOL 1995 cup final between Rosario Central vs Atletico Mineiro
It has not happened in Europe maybe it has happened in other continents. Can anyone find a match where a team came from a 5 goal deficit to win in second leg(playoff,tiebreaker,any).