2018 AFC Champions League group stage

The draw for the group stage was held on 6 December 2017, 16:30 MYT (UTC+8), at the AFC House in Kuala Lumpur, Malaysia.^[3][4] The 32 teams were drawn into eight groups of four: four groups each in the West Region (Groups A–D) and the East Region (Groups E–H). Teams from the same association could not be drawn into the same group.

The seeding of each team in the draw was determined by their association and their qualifying position within their association. The mechanism of the draw was as follows:

• For the West Region, a draw was held for the three associations with three direct entrants (United Arab Emirates, Iran, Qatar) to determine the seeds 1 placed in order for Groups A, B and C. The remaining teams were then allocated to the groups according to the rules set by AFC.
• For the East Region, a draw was held for the two associations with three direct entrants (South Korea, Japan) to determine the seeds 1 placed in order for Groups E and F. The remaining teams were then allocated to the groups according to the rules set by AFC.

The following 32 teams entered into the group-stage draw, which included the 24 direct entrants and the eight winners of the play-off round of the qualifying play-offs, whose identity was not known at the time of the draw.

Region	Groups	Seed 1	Seed 2	Seed 3	Seed 4
West Region	A–D	Al-Jazira	Al-Wahda	Al-Wasl	Al-Ain (Play-off West 1)
		Persepolis	Esteghlal	Tractor Sazi	Zob Ahan (Play-off West 2)
		Al-Duhail	Al-Sadd	Al-Rayyan	Al-Gharafa (Play-off West 3)
		Al-Hilal	Al-Ahli[note 1]	Lokomotiv Tashkent[note 1]	Nasaf Qarshi (Play-off West 4)
East Region	E–H	Jeonbuk Hyundai Motors	Ulsan Hyundai	Jeju United	Suwon Samsung Bluewings (Play-off East 1)
		Kawasaki Frontale	Cerezo Osaka[note 2]	Kashima Antlers	Kashiwa Reysol (Play-off East 2)
		Guangzhou Evergrande	Shanghai Shenhua	Tianjin Quanjian (Play-off East 4)	Shanghai SIPG (Play-off East 3)
		Sydney FC	Kitchee[note 3]	Melbourne Victory	Buriram United[note 3]

In the group stage, each group was played on a home-and-away round-robin basis. The winners and runners-up of each group advanced to the round of 16 of the knockout stage.

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 10.5):^[2]

1. Points in head-to-head matches among tied teams;
2. Goal difference in head-to-head matches among tied teams;
3. Goals scored in head-to-head matches among tied teams;
4. Away goals scored in head-to-head matches among tied teams;
5. 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;
6. Goal difference in all group matches;
7. Goals scored in all group matches;
8. Penalty shoot-out if only two teams are tied and they met in the last round of the group;
9. 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);
10. Team from the higher-ranked association.

The schedule of each matchday was as follows.^[1]

• Matches in the West Region were played on Mondays and Tuesdays (two groups on each day).
• Matches in the East Region were played on Tuesdays and Wednesdays (two groups on each day).

In light of the deterioration of Iran–Saudi Arabia relations since 2016, which caused matches between teams from Iran and Saudi Arabia to be played on neutral venues in 2016 and 2017, and the Qatar diplomatic crisis since 2017, which led to travel bans imposed by Saudi Arabia and United Arab Emirates to Qatar, the AFC reiterated that matches should be played on a home-and-away basis as normal instead of on neutral venues, and would try to mediate the situation with the concerned associations (Iran, Qatar, Saudi Arabia, United Arab Emirates), such that a solution could be found regarding matches between teams from Iran/Qatar and Saudi Arabia/United Arab Emirates.^[5][6][7][8] In the end, the same arrangements were made as of the previous season, where matches between Iran and Saudi Arabia were played on neutral venues, while teams from Saudi Arabia and United Arab Emirates must travel to Qatar to play away matches.^[9][10]