The away goals rule is not a difficult concept to understand but its use can vary from competition to competition.
Thankfully, in Uefa's flagship club tournaments, the rule is applied in a simple fashion.
What is the away goals rule?
For example, Tottenham reached the 2019 Champions League final on away goals after drawing 3-3 over two legs in their semi-final against Ajax.
Tottenham lost the first leg at home 1-0 but won the away leg 3-2, with Lucas Moura’s 96th-minute strike levelling the score on aggregate and forcing the away goals tiebreaker.
If both teams have scored the same number of goals home and away after 180 minutes of football, then a result cannot be determined by away goals.
A standard, additional 30-minute period of extra time is played.
Do away goals count in extra time?
Yes. In both the Champions League and Europa League, away goals still count in extra time.
If the away team takes the lead in extra time under the away goals rule, the home team must score twice to progress.
Chelsea were knocked out of the 2014-15 Champions League by Paris Saint-Germain on away goals in extra time.
After drawing 1-1 in the first leg in Paris, another 1-1 draw at Stamford Bridge after 90 minutes forced extra time.
Eden Hazard’s 96th-minute penalty gave Chelsea the lead but David Luiz’s header 18 minutes later levelled the aggregate score at 3-3. PSG held on to go through on away goals.
Do away goals count at neutral venues?
This year, several English clubs will play Champions League and Europa League away legs at neutral venues due to Covid-19 restrictions.
Away goals will still count and be used as a tiebreaker if the aggregate score is level after 180 minutes, even though only one team will have played at their home ground.
Do away goals 'count double'?
This is just a figure of speech, one which only causes confusion about a simple rule. Away goals in and of themselves do not 'count double'.
If a visiting team is losing 6-0 on aggregate but suddenly pulls one back, the score is 6-1, not 6-2, and they would still need to score at least another five to progress.