Billed the ‘Battle of Britain’, Celtic had already gone to Elland Road and won 1-0 in the first-leg, but this was the game no-one in the green half of Glasgow wanted to miss.
The demand for tickets was incredulous. So much so, Celtic decided to move the game to Hampden Park to avail of its greater capacity.
136,505 ticketed fans turned up on the night, 15 April 1970, fifty-one years ago. It remains a record crowd for any UEFA competition match and is unlikely ever to be beaten.
Both sides played in their national cup finals on the previous Saturday, Celtic going down surprisingly 1-3 to Aberdeen, captained by a young Martin Buchan who would go on to become the first man to captain Scottish and FA Cup winning teams when he completed the feat in 1977 with Manchester United.