A two-legged tie in football is a match between two football clubs or national teams in two separate matches are played to determine the result of the tie. A two-legged tie is mostly used in knockout competitions (such as the UEFA Champions League and the UEFA Cup) in which each team plays one game known as the leg) at home and one game away from home at the opponent’s stadium.
Two-legged ties are used to determine the winner of the ties without allowing any team to have any “home advantage”. On most cases, the winner of the two-legged tie is the team that manages to get a better aggregate score, that is score more than the other over the two legs.
On certain occasions, the two teams may end up scoring the same umber of goals over the two legs. On these occasions, at times the away goals rule is applied (in this rule, the team that scored the more away goals is declared the winner of the tie) while on other times the tie is decided by extra time and/or penalty. Sometimes replays are also used.