The 2018 AFC Champions League group stage was played from 12 February to 18 April 2018.[1] A total of 32 teams competed in the group stage to decide the 16 places in the knockout stage of the 2018 AFC Champions League.[2]
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:
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.
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]
The schedule of each matchday was as follows.[1]
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]