The 2018 AFC Champions League knockout stage was played from 7 May to 10 November 2018. A total of 16 teams competed in the knockout stage to decide the champions of the 2018 AFC Champions League.
The winners and runners-up of each of the eight groups in the group stage advanced to the round of 16, with both West Region (Groups AâÂÂD) and East Region (Groups EâÂÂH) having eight qualified teams.
<section begin=Format /> In the knockout stage, the 16 teams played a single-elimination tournament, with the teams split into the two regions until the final. Each tie was played on a home-and-away two-legged basis. The away goals rule, extra time (away goals do not apply in extra time) and penalty shoot-out were used to decide the winner if necessary (Regulations Article 11.3).<section end=Format />
The schedule of each round was as follows. Matches in the West Region were played on Mondays and Tuesdays, while matches in the East Region were played on Tuesdays and Wednesdays.
The bracket of the knockout stage was determined as follows:
<section begin=Bracket /> The bracket was decided after the draw for the quarter-finals, which was held on 23 May 2018, 16:00 MYT (), at the AFC House in Kuala Lumpur, Malaysia.
<section end=Bracket />
<section begin=Round of 16 /> In the round of 16, the winners of one group played the runners-up of another group from the same region, with the group winners hosting the second leg, and the matchups determined by the group stage draw.
|+West Region
|+East Region
<section end=Round of 16 />
4âÂÂ4 on aggregate. Persepolis won on away goals.
Al-Sadd won 4âÂÂ3 on aggregate.
Esteghlal won 3âÂÂ2 on aggregate.
Al-Duhail won 8âÂÂ3 on aggregate.
2âÂÂ2 on aggregate. Tianjin Quanjian won on away goals.
Jeonbuk Hyundai Motors won 4âÂÂ3 on aggregate.
Suwon Samsung Bluewings won 3âÂÂ1 on aggregate.
Kashima Antlers won 4âÂÂ3 on aggregate.
<section begin=Quarter-finals /> The draw for the quarter-finals was held on 23 May 2018. In the quarter-finals, the four teams from the West Region played in two ties, and the four teams from the East Region played in two ties, with the matchups and order of legs decided by draw, without any seeding or country protection.
|+West Region
|+East Region
<section end=Quarter-finals />
Al-Sadd won 5âÂÂ3 on aggregate.
Persepolis won 3âÂÂ2 on aggregate.
Kashima Antlers won 5âÂÂ0 on aggregate.
3âÂÂ3 on aggregate. Suwon Samsung Bluewings won 4âÂÂ2 on penalties.
<section begin=Semi-finals /> In the semi-finals, the two quarter-final winners from the West Region played each other, and the two quarter-final winners from the East Region played each other, with the order of legs determined by the quarter-final draw.
|+West Region
|+East Region
<section end=Semi-finals />
Persepolis won 2âÂÂ1 on aggregate.
Kashima Antlers won 6âÂÂ5 on aggregate.
<section begin=Final />
In the final, the two semi-final winners played each other, with the order of legs (first leg hosted by team from the East Region, second leg hosted by team from the West Region) reversed from the previous season's final.
Kashima Antlers won 2âÂÂ0 on aggregate.<section end=Final />