The 1986 FIFA World Cup knockout stage was the second and final stage of the 1986 FIFA World Cup finals in Mexico. The stage began on 15 June 1986, and ended with the final at the Estadio Azteca in Mexico City on 29 June 1986.
Sixteen teams advanced to the knockout stage to compete in a single-elimination style tournament: The top two teams from each of the six groups, as well as the best four third-placed teams. In the round of 16, the four third-placed teams played against four of the group winners from group A-D, with the remaining two group winners from group E and F taking on two of the group runners-up; the remaining four runners-up were paired off against each other. The winners of the eight round of 16 matches were then paired together in the quarter-finals, the winners of which played against each other in the semi-finals.
The ties in each round were played over a single match; in the event that scores were level after 90 minutes, the teams would play an additional 30 minutes of extra time, divided into two 15-minute halves, to determine the winner. If the scores remained level after extra time, the teams would contest a penalty shootout.
A third place match was also held on the day before the final, between the two losing teams of the semi-finals.