Fnatic and MAD Lions each won two matches on Thursday as the League of Legends World Championship Play-In event began in Mexico City.
Fnatic sit atop Group A after the opening day, while MAD Lions lead Group B.
The event's 12 teams are divided into two groups for an opening round that consists of a single round robin. After five best-of-one matches per club, the top team in each group will move straight into the Worlds' group stage, while the second-, third- and fourth-place team in each group will head to a second Play-In phase.
Round 2 of Play-In action, scheduled for Monday and Tuesday, will feature best-of-five matches. The third- and fourth-place team in each group will square off for the right to face the second-place team from the other group. The winners of each of the last two matches head to the Worlds' group stage, while all other teams will head home.
Twelve teams are already through to the group stage: JD Gaming, Top Esports, Edward Gaming, Gen.G Esports, T1, DAMWON Gaming, Rogue, G2 Esports, Cloud9, 100 Thieves, CTBC Flying Oyster and GAM Esports.
Fnatic opened with victories over Evil Geniuses, in 29 minutes on blue, and Chiefs Esports Club, in 30 minutes on red. Germany's Elias "Upset" Lipp had a combined 15-0-4 kill-death-assist differential for Fnatic.
MAD Lions handled Isurus, in 38 minutes on red, and Istanbul Wildcats, in 37 minutes on blue. Sweden's William "UNF0RGIVEN" Nieminen paced MAD Lions with a combined 17-2-12 K-D-A differential.
In other Group A action on Thursday, Beyond Gaming defeated LOUD in 29 minutes on red, and LOUD downed DetonatioN FM in 23 minutes on red.
In Group B, Saigon Buffalo beat Istanbul Wildcats in 35 minutes on blue, and DRX outlasted Royal Never Give Up in 42 minutes on blue.
Eight matches are scheduled for Friday:
--Group A: Fnatic vs. DetonatioN FM
--Group A: Evil Geniuses vs. LOUD
--Group A: DetonatioN FocusMe vs. Chiefs Esports Club
--Group A: Evil Geniuses vs. Beyond Gaming
--Group B: Saigon Buffalo vs. Isurus
--Group B: DRX vs. Saigon Buffalo
--Group B: Royal Never Give Up vs. MAD Lions
--Group B: Istanbul Wildcats vs. DRX
League of Legends World Championship Play-In opening-round group standings
1. Fnatic, 2-0
2. Beyond Gaming, 1-0
3. LOUD, 1-1
T4. Chiefs Esports Club, 0-1
T4. DetonatioN FocusMe, 0-1
T4. Evil Geniuses, 0-1
1. MAD Lions, 2-0
T2. DRX, 1-0
T2. Saigon Buffalo, 1-0
T4. Isurus, 0-1
T4. Royal Never Give Up, 0-1
6. Istanbul Wildcats, 0-2
--Field Level Media