G2, FaZe and FURIA have to earn their spots at the $250,000 event, while Astralis and Vitality were handed invites.

ESL unveiled the teams that will take part in the IEM Summer 2021 closed qualifier, kicking off on April 26, as well as the squads invited for the main event in June.

Only three teams from the qualifier will advance to the tournament, with the competition for those spots fierce. Two top-10 sides, G2 and FURIA, are in competition, as is OG, FunPlus Phoenix, and FaZe.

Meanwhile, six ESL-partnered teams have been handed invites, including fnatic and Evil Geniuses, while the likes of Gambit and HEROIC earned their spots on the basis of their ESL world ranking.

The IEM Summer Closed Qualifier will take place on April 26-28, using a two-stage format. In the first stage, the four qualified teams, including SKADE and Movistar Riders, will face off against four lower-seed invited teams. The losers of those matches will be eliminated, while the winners advance to a second, double-elimination stage featuring four high-seed invites.

The initial matchups for the closed qualifier look as follows:

Stage 1:
ENCE vs. Movistar Riders
OG vs. Trident
FunPlus Phoenix vs. SKADE
MOUZ vs. K23

Stage 2:
FURIA vs. TBD
FaZe vs. TBD
BIG vs. TBD
G2 vs. TBD

In terms of the final event which boasts a $250,000 prize pool, 12 of the 16 teams are now know. Imperial and Extra Salt were the first confirmed teams, having qualified through regional competition. CIS trio Gambit, Virtus.pro, and Spirit were handed spots at the event based on their ranking, as were ESL Pro League Season 13 winners HEROIC.

Six more slots were filled will ESL's partner teams. The list includes Astralis, Vitality, Complexity, as well as Swedish duo Ninjas in Pyjamas and fnatic. The final partner spot was reserved for a North American representative, which in this case is Evil Geniuses.

From the slots that haven't been taken, three are reserved for closed qualifier teams, with the final one left to be decided through an "EPT Connection" event, ESL National Championships Global Playoff: Spring 2021.

Team list for IEM Summer 2021: