The knockout stage of the 2018 FIFA World Cup was the second and final stage of the competition, following the group stage. It began on 30 June with the round of 16 and ended on 15 July with the final match, held at the Luzhniki Stadium in Moscow. The top two teams from each group (16 in total) advanced to the knockout stage to compete in a single-elimination style tournament. A third place play-off was also played between the two losing teams of the semi-finals.

France won the final 4–2 against Croatia for their second title, while Belgium won the third place play-off 2–0 over England.

All times listed are local time.

In the knockout stage, if a match was level at the end of 90 minutes of normal playing time, extra time was played (two periods of 15 minutes each), where each team was allowed to make a fourth substitution. If still tied after extra time, the match was decided by a penalty shoot-out to determine the winners.

The top two placed teams from each of the eight groups qualified for the knockout stage.

The teams had faced each other in 11 previous matches, including two World Cup group stage matches, both won by Argentina (1–0 in 1930, and 2–1 in 1978).

After nine minutes, Antoine Griezmann's 25-yard free-kick crashed back off Franco Armani's crossbar. After picking the ball up deep inside his own half, Kylian Mbappé set off on a run that was halted when Marcos Rojo hauled him down just inside the area. Griezmann stepped up and converted from the spot, sending the ball low to Armani's right. Four minutes before the interval, Ángel Di María shot from distance with his left foot to beat Hugo Lloris into the top right corner of the net. Three minutes after the restart, Éver Banega's free-kick was headed out towards Lionel Messi whose effort towards goal from the right was diverted past Lloris by Gabriel Mercado with his left leg. Nine minutes later, Lucas Hernandez's cross from the left found Benjamin Pavard, who shot a half-volley from outside the area, sending it into Armani's top-right corner. Pavard’s goal was later voted the best goal of the tournament. Mbappé put France ahead again in the 64th minute when he picked up a loose ball in the left of the area, found a yard of space and fired in low with his left foot under Armani. His second – a first-time low finish from the right of the penalty area with his right foot – followed just four minutes later. Sergio Agüero nodded home in the third minute of stoppage time from a Messi cross from the right. Argentina, however, was unable to equalize to send the match to extra-time from being eliminated of the tournament . This game was hailed as "one of the greatest World Cup games of all time" by The Independent.

With this match, Didier Deschamps became the longest-serving coach in the history of the France national team with his 80th game in charge of France, moving ahead of his predecessor Raymond Domenech. Mbappé became the first teenager to score at least twice in a World Cup tournament since Michael Owen in 1998, and the first teenager to score at least twice in a single World Cup match since Pelé netted twice for Brazil against Sweden in the 1958 final. Argentina became the first team to score at least three goals but still lose a World Cup match since the Soviet Union vs Belgium in 1986, and was also the first time that Argentina had been eliminated in the round of 16 since 1994, when they were defeated by Romania.