The final group stage fixtures are played at exactly the same time to ensure that both matches are fully contested by both teams. If only one match remains in a World Cup group, the two teams playing will already know exactly what they need to qualify. This can lead to matches being played in an unsporting manner, where teams can agree to settle for a result that benefits them both.
The matches are played at the same time in order to prevent any pre-match agreements that could take place between teams to elicit a result in their favour. Teams could gain an unfair advantage if the final matches of the same group are held separately because sides playing second will know what they need to do in order to qualify for the next stage of the World Cup.
The final fixtures of the group stages weren’t always played simultaneously. It took a controversial exploitation of circumstances in the 1982 World Cup in Spain to force FIFA into making a rule change.
The infamous fixture took place at El Molinon stadium in Gijon, and has come to be known as the “Disgrace of Gijón”.
West Germany and Austria went into the game knowing that victory by one or two goals for West Germany would qualify both teams from Group 2, at the expense of Algeria who played their final group game a day earlier.
West Germany took the lead inside the first 10 minutes of the match, which then descended into a largely non-competitive affair with neither side making a concerted effort to score.
The game finished 1-0 meaning Algeria were eliminated, and while FIFA ruled that no rules had been broken the match led to a revised group system in future tournaments with the final two games in each group played simultaneously.