Twelve of these would go through to a second stage, comprising four groups of three, with the winners of those groups proceeding to the semi finals.
Despite some reservations about the new format, it produced an excellent tournament, which burst into life on the opening night with the holders Argentina going down 1-0 to Belgium, although both sides would eventually qualify for the next stage.
There was another big early upset as Algeria stunned West Germany 2-1, but the African side were denied a place in the next stage when the Germans beat Austria 1-0, a result which took both of those teams through.
Northern Ireland made their first appearance in 24 years, and beat the host nation 1-0 on the way to finishing top of their group. They would later find themselves needing to beat France in Madrid to reach the semi finals, but lost 4-1 and were knocked out.
This 12-team second stage also produced one of the great World Cup matches, in which Brazil needed to draw with Italy, but were beaten 3-2 as a Paolo Rossi hat trick took the Italians through instead.
Rossi got two more in the semi finals as Italy beat Poland 2-0, while the other semi final is remembered largely for a horrific challenge by Germany keeper Harald Schumacher on Patrick Battiston, which knocked the France defender unconscious.
The match went to extra time, in which the Germans came from 3-1 down to draw 3-3, before going on to win 5-4 on penalties.
Italy beat them 3-1 in the final however, matching Brazil’s achievement of winning the tournament three times, and making their 40-year-old goalkeeper and captain Dino Zoff the oldest player ever to win a World Cup.