The 2018 AFC Cup knockout stage was played from 7 May to 27 October 2018. A total of 11 teams competed in the knockout stage to decide the champions of the 2018 AFC Cup.
The following teams advanced from the group stage:
<section begin=Format /> In the knockout stage, the 11 teams played a single-elimination tournament. Each tie was played on a home-and-away two-legged basis, except the final which was played as a single match. The away goals rule (for two-legged ties), 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 (W: West Asia Zone; A: ASEAN Zone). Matches in the West Asia Zone were played on Mondays and Tuesdays, while matches in the ASEAN Zone and the Inter-zone play-offs 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 Zonal finals and the Inter-zone play-off semi-finals, which was held on 23 May 2018, 15:00 MYT (), at the AFC House in Kuala Lumpur, Malaysia.
<section end=Bracket />
<section begin=Zonal semi-finals /> In the Zonal semi-finals, the four qualified teams from the West Asia Zone (Groups AâÂÂC) played in two ties, and the four qualified teams from the ASEAN Zone (Groups FâÂÂH) played in two ties, with the matchups and order of legs determined by the group stage draw and the identity of the best runners-up.
|+West Asia Zone
|+ASEAN Zone
<section end=Zonal semi-finals />
Al-Jazeera won 2âÂÂ1 on aggregate.
Al-Quwa Al-Jawiya won 5âÂÂ3 on aggregate.
Home United won 6âÂÂ3 on aggregate.
CeresâÂÂNegros won 6âÂÂ5 on aggregate.
<section begin=Zonal finals /> The draw for the Zonal finals was held on 23 May 2018. In the Zonal finals, the two winners of West Asia Zonal semi-finals played each other, and the two winners of ASEAN Zonal semi-finals played each other, with the order of legs decided by draw. The winners of the West Asia Zonal final advanced to the final, while the winners of the ASEAN Zonal final advanced to the Inter-zone play-off semi-finals.
|+West Asia Zone
|+ASEAN Zone
<section end=Zonal finals />
Al-Quwa Al-Jawiya won 4âÂÂ1 on aggregate.
Home United won 3âÂÂ1 on aggregate.
<section begin=Inter-zone play-off semi-finals /> The draw for the Inter-zone play-off semi-finals was held on 23 May 2018. In the Inter-zone play-off semi-finals, the four zonal winners other than the West Asia Zone played in two ties, i.e., the winners of the Central Asia Zone (Group D), the winners of the South Asia Zone (Group E), the winners of the East Asia Zone (Group I), and the winners of the ASEAN Zonal final (whose identity was not known at the time of the draw), with the matchups and order of legs decided by draw, without any seeding.
<section end=Inter-zone play-off semi-finals />
April 25 won 11âÂÂ1 on aggregate.
Altyn Asyr won 5âÂÂ2 on aggregate.
<section begin=Inter-zone play-off final /> In the Inter-zone play-off final, the two winners of the Inter-zone play-off semi-finals played each other, with the order of legs determined by the Inter-zone play-off semi-final draw. The winners of the Inter-zone play-off final advanced to the final.
<section end=Inter-zone play-off final />
3âÂÂ3 on aggregate. Altyn Asyr won on away goals.
<section begin=Final />
In the final, the winners of the West Asia Zonal final and the winners of the Inter-zone play-off final played each other, with the host team (winners of the West Asia Zonal final) alternated from the previous season's final. <section end=Final />