The away-goals rule was abolished on Thursday by UEFA after 56 years as a fundamental way of deciding matches in its European club competitions. (More Football News)
The move was often proposed in recent years by club coaches who felt an idea from the 1960s was no longer relevant.
Games now tied on aggregate score after the regulation 90 minutes in the second leg will go direct to extra time and then to a penalty shootout.
UEFA president Aleksander Ceferin cited the "unfairness, especially in extra time, of obliging the home team to score twice when the away team has scored."
UEFA cited several factors that "blurred the lines between playing at home and away" including more television coverage to better understand opponents' styles, comfortable travel and better playing surfaces.
Ceferin said the rule outlived its usefulness and inhibited home teams from attacking "because they fear conceding a goal that would give their opponents a crucial advantage."