The 2018 World Cup in Russia will begin in 21 days and use a format familiar to soccer fans around the world: round-robin play in eight different groups followed by a 16-team knockout stage.

But the current format was first used in 1986.

In 1978, the eight teams that advanced out of the initial group phase competed in a second round-robin phase consisting of two sets of four squads.

Argentina and Brazil both competed in Group B in the second phase and were locked in an intense battle for a berth in the tournament's final on June 25. The second-place team would have to settle for a spot in the third-place playoff.

Heading into their final round-robin matches, Brazil and Argentina were tied on points (three apiece) but the former had a slight one-goal lead in the goal differential.

Brazil was the first to finish its match on June 21, defeating Poland 3-1 to boost its lead in the differential to three goals.

This meant Argentina needed four goals to advance to the final against the Netherlands, which had won Group A earlier that same day with a 2-1 win over Italy.

Peru started well and hit the left upright with a shot in the early going, but it was all Argentina after that.

Mario Kempes opened the scoring in the 21st minute for the Albiceleste, which took a 2-0 lead into the intermission on a goal by Alberto Tarantini just before halftime.

The hosts then poured it on in the second half, getting a second goal from Kempes, two by Leopoldo Luque and one from Rene Houseman.

The result is considered suspicious, among other reasons, because Argentina's then-dictator, Jorge Videla, reportedly visited the Peruvians' locker room prior to the contest and made an appeal to "South American solidarity."

Brazil ended up defeating Italy 2-1 in the third-place playoff on June 24, while Argentina lifted its first World Cup trophy with a 3-1 extra-time win over the Netherlands the following day.