Each of the 12 premier League of Legends leagues had a team representing them. This was the first edition in which all competitive regions began in the same stage of the tournament, unlike previous years where the winners of the minor leagues had to win play-in matches to face teams from the larger regions.[1][2]
"Starts Right Here" was the tournament's theme song, put together by Foreign Air, and Kenny Mason.[3]
The format for 2021 replaces the play-in stage used from 2017 to 2019 with a group stage featuring all regions. The 12 teams were seeded into 3 groups from 4 seeding pools. This is the first time that teams from Europe (LEC), South Korea (LCK) and China (LPL) will not automatically qualify for the second stage (known as the rumble stage, formerly the group stage of the main event) but have to compete with all remaining teams.
The top two teams in each group in group stage qualify for the rumble stage, a six team double round robin. The top four teams of the rumble stage advance to the single elimination knockout stage.
The number of regions decreased from 13 at MSI 2019 to 12, due to the merger of Taiwan/Hong Kong/Macau (LMS) and Southeast Asian (LST) professional leagues into the PCS for 2020.
Pools of group stage are determined by the achievements of regions during the MSI and Worlds events from the two years prior.