The 2021 AFC Cup group stage was played from 14 May to 24 August 2021.[1] A total of 38 teams should have competed in the group stage to decide the 12 places in the knockout stage of the 2021 AFC Cup.[2]
Draw
The draw for the group stage was held on 27 January 2021, 14:30 MYT (UTC+8), at the AFC House in Kuala Lumpur, Malaysia.[3] The 38 teams were drawn into nine groups of four and one group of three (in the Central Asia Zone): three groups each in the West Asia Zone (Groups A–C) and the ASEAN Zone (Groups G–I), two groups in the Central Asia Zone (Groups E–F), and one group each in the South Asia Zone (Group D) and the East Asia Zone (Group J). For each zone, teams were seeded into four pots and drawn into the relevant positions within each group, based on their association ranking and their seeding within their association, in consideration of technical balance between groups. Teams from the same association in zones with more than one group (West Asia Zone, Central Asia Zone, and ASEAN Zone) could not be drawn into the same group.[4]
Originally, 39 teams entered into the group stage draw, which included the 35 direct entrants and the four winners of the play-off round of the qualifying play-offs, whose identity was not known at the time of the draw. However, after the withdrawal of teams from Oman and Myanmar, and promotion of Kaya–Iloilo to AFC Champions League group stage, only 37 teams would compete, including 34 direct entrants, one winner of the play-off round, and two winners of the preliminary round.
The teams were ranked according to points (3 points for a win, 1 point for a draw, 0 points for a loss). If tied on points, tiebreakers were applied in the following order (Regulations Article 8.3):[2]
Goals scored in head-to-head matches among tied teams;
Away goals scored in head-to-head matches among tied teams; (not applicable since the matches were played in a centralised venue)
If more than two teams are tied, and after applying all head-to-head criteria above, a subset of teams are still tied, all head-to-head criteria above are reapplied exclusively to this subset of teams;
Goal difference in all group matches;
Goals scored in all group matches;
Penalty shoot-out if only two teams playing each other in the last round of the group are tied;
Disciplinary points (yellow card = 1 point, red card as a result of two yellow cards = 3 points, direct red card = 3 points, yellow card followed by direct red card = 4 points);
Source: AFC Rules for classification: Tiebreakers (H) Hosts
^After matches in ASEAN Zone was cancelled, there are only three teams which qualified to the Inter-zone play-off semi-finals, i.e., the winners of the South Asia Zone (Group D), the winners of the East Asia Zone (Group J), and the winners of the Central Zonal final. The three Zonal champions will be drawn into two pairings where one club will get a bye to the Inter-zone play-off final, which happened for Lee Man.
Source: AFC Rules for classification: 1) Points; 2) Goal difference; 3) Goals scored; 4) Disciplinary points; 5) Drawing of lots.
Notes
^ abcOn 23 April 2021, the AFC announced that the two teams from Oman, Al-Seeb and Al-Nasr, withdrew from the group stage after the draw, after the suspension of all international and domestic sporting activities due to the COVID-19 pandemic in Oman. As a result, the AFC decided to cancel the play-off round match between Markaz Shabab Al-Am'ari and Al-Kuwait, and promote both teams to the group stage.[5] Markaz Shabab Al-Am'ari would occupy position C2 (original position of Al-Seeb) and Al-Kuwait would occupy position C4 (original position of play-off round winner), while Al-Nasr (position A4) would not be replaced.
^ abThe standby teams would replace a team from the same association which played in the AFC Champions League qualifying play-offs and advanced to the AFC Champions League group stage. Since AGMK advanced from the AFC Champions League qualifying play-offs to the group stage, Nasaf, which were the standby team from Uzbekistan, replaced AGMK in the AFC Cup group stage. There is no standby team from Philippines (for Kaya–Iloilo)
^ abcdOn 30 April 2021, the AFC announced that the two teams from Myanmar, Shan United and Hanthawady United, withdrew from the group stage and play-off stage respectively after the draw, due to the state of emergency caused by the 2021 Myanmar coup d'état. As a result, the AFC decided to cancel the two play-off round matches, and promote Persipura Jayapura and the two preliminary stage winners to the group stage.[6] Persipura Jayapura would occupy position H4 (original position of play-off round winner 2), the preliminary round winner 1 would occupy position G4 (original position of play-off round winner 1), and the preliminary round winner 2 would occupy position I2 (original position of Shan United).
Al-Salt
Al-Hidd
Al-Ahed
Markaz Shabab Al-Am'ari
Tishreen
Al-Kuwait
ATK Mohun Bagan
Bashundhara Kings
Maziya
Nasaf 
Altyn Asyr
Khujand
Alay
Visakha
Lion City Sailors
Hà Nội
Lalenok United
TBD (Winners of Preliminary ASEAN 2.1)
Kedah
Bali United
Eastern
Tainan City
Athletic 220
