DRX defeated Isurus in Group B on Saturday to remain unbeaten at the League of Legends World Championship Play-In event in Mexico City.

DRX improved to 4-0 with a 23-minute win on red. South Koreans Kim "Deft" Hyuk-kyu and Cho "BeryL" Geon-hee posted matching kills-deaths-assists ratios of 5/1/10 to lead DRX.

In other Group B action Saturday, Royal Never Give Up beat Istanbul in 31 minutes on blue, RNG beat Isurus in 26 minutes on blue and MAD Lions beat Saigon Buffalo in 35 minutes on blue.

In Group A, Evil Geniuses bested Chiefs Esports Club in 25 minutes on blue, Beyond Gaming topped Chiefs Esports Club in 26 minutes on red, DetonatioN FM beat Beyond Gaming in 40 minutes on red and LOUD upended Fnatic in 28 minutes on blue. Fnatic (3-1) suffered their first loss.

Diego "Brance" Amaral of Brazil led LOUD with a K-D-A ratio of 8-1-7.

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.

Six matches are scheduled for Sunday:

Group A: Beyond Gaming vs. Fnatic

Group A: LOUD vs. Chiefs Esports Club

Group A: DetonatioN FocusMe vs. Evil Geniuses

Group B: Istanbul Wildcats vs. Isurus

Group B: DRX vs. MAD Lions

Group B: Royal Never Give Up vs. Saigon Buffalo

League of Legends World Championship Play-In opening-round group standings

Group A

T1. Fnatic, 3-1

T1 Evil Geniuses, 3-1

T3. Beyond Gaming, 2-2

T3. DetonatioN FocusMe, 2-2

T3. LOUD, 2-2

6. Chiefs Esports Club, 0-4

Group B

1. DRX, 4-0

T2. MAD Lions, 3-1

T2. Royal Never Give Up, 3-1

4. Saigon Buffalo, 2-2

T5. Isurus, 0-4

T5. Istanbul Wildcats, 0-4