The ESL One Rio Major will feature a seeding made by the participating teams, ESL's VP of Pro Gaming, Michal "Carmac" Blicharz, revealed on the HLTV Confirmed show.
The system will largely be the same as the one used for the previous Major hosted by ESL, IEM Katowice 2019, where ahead of the first two stages the participating teams themselves ranked their opponents from 1-15, which was then used to seed teams into the opening round of matches in the Swiss format.
In this system, the seeding of each team is adjusted after every round based on the opponent they faced and on the result, with teams who pulled off an upset gaining a significant portion of the difference between theirs and the opponent's seeding (and vice versa), for example.
One important change that will be introduced to the player-selected ranking at ESL One Rio is that, before the second stage, it will not be allowed to seed a team below one they outplaced in the first stage. As an example, a team that went 3-0 in the New Challengers Stage cannot be seeded below one who advanced with a 3-1 record. Any team coming from the New Challengers Stage will still be allowed to be placed above the Legends.
The news was revealed during the ninth episode of HLTV Confirmed, in which Carmac also discussed a plethora of other topics surrounding the recently-announced changes to ESL Pro League and Valve's plans to utilize two extra tournaments to find the eight Legends and eight Challengers invited to the 2020 Fall Major.