Sporting were the favourites for the competition and included such stars as Brazilian Chico and Argentinean Hector Yazalde.
At Ibrox in the first leg, Rangers raced to a brilliant 3-0 interval lead thanks to two goals from Colin Stein and one from Willie Henderson. All three goals came from brilliant free-kick moves within the first half-hour. The Ibrox crowd of 50,000 were going wild and Rangers really should have been further ahead when the half-time whistle sounded.
In the second half Sporting staged a dramatic fight back and scored twice through Chico and Pedro Gomez to leave Rangers with a slender lead where once it had looked comfortable. Many people thought Rangers had blown their chances, but the players were to prove that they possessed great reserves of strength and fight.
Second leg - 3rd November 1971
The Rangers visit to Portugal was full of drama for many reasons. The players and officials had assembled at Glasgow airport at 9am on Monday, but Airport delays en route to Portugal meant that the usual nine hour journey took an agonising thirty-five hours. It meant they did not reach their hotel until the Tuesday evening, with the game due to go ahead 24 hours later! Hardly ideal preparations!
A training session was squeezed in the next morning and a few hours later the travel weary squad were coming out of the tunnel for the match itself.
The match was played in the Jose d'Alvalade Stadium in an intense atmosphere and watched by a crowd of 60,000.
A team of "bongo" drummers beat out a macabre jungle rhythm throughout the game, rockets were set off, hatred seethed from the terraces and even the Tanoy announcer booed The Rangers over the PA system.
Sporting took a 24th minute lead through Yazalde, but Colin Stein scored a great equaliser within sixty seconds. Just before half-time Laranjeira restored Sporting's lead. In the first minute of the second half, Colin Stein scored again to equalise.
The Ibrox club were turning in a fantastic performance but there was heartbreak in seventy-two minutes when Ronnie McKinnon suffered a broken leg. Ronnie, his face contorted with pain was stretchered off, and was replaced in the side by Dave Smith. Shortly before the end Gomez scored to make the score 3-2 for Sporting after ninety minutes and 5-5 on aggregate with both clubs having two away goals.
In extra time Rangers drew from their depths of stamina and remarkably scored through Willie Henderson. However, again close to time Peres scored with a penalty after a Colin Jackson handball, to make the score 4-3 to Sporting, but 6-6 on aggregate.
Surely Rangers were through on away goals but not according to Dutch referee Laurens van Raavens, who insisted on a penalty shoot-out to decide the tie. Rangers' penalties were poor, they missed four and lost the shoot-out.
Rangers had lost and were out.
Dramatically, hopes were raised back in the dressing room when Sports Journalist with the Scottish Daily Express, John MacKenzie produced a UEFA rule book claiming the rules stated Rangers had won. The book stated that contrary to the ref's decision, away goals in extra time did indeed count as double.
Willie Waddell was quickly informed and the referee was approached. At a hastily convened meeting consisting of Willie Waddell, Sporting officials, the referee and UEFA Officials the result was thrashed out, but it was in fact the next day when Rangers were back in Scotland when news came through that the result had been officially overturned.
After one of the most dramatic and frustrating few days in the club's history, Rangers were through to the Third Round.
Angry Sporting officials even flew to UEFA Headquarters in Switzerland to plead their case but their journey was a wasted one - Rangers were through.
The only down side was Ronnie McKinnon's broken leg.