Gen.G completed the 2025 League of Legends Champions Korea regular season with an unblemished 18-0 record after securing victories over KT Rolster and OKSavingsBank BRION during Week 9 at the LCK Arena in Seoul. The team carried momentum from a flawless 9-0 first round into its second round, adding two more wins between May 28 and June 1 to become only the second squad in league history to finish a season undefeated.

In their first match of the week on May 29, Gen.G rallied against KT Rolster. Trailing 1-7 in kills by the 22-minute mark of the deciding game, Gen.G maintained a gold lead and seized control near Baron. Renekton player Kim "Kiin" Ki-in delivered four kills in a skirmish around the objective, turning the tide. The team closed out the game at 38 minutes after winning a subsequent fight near Baron, clinching a 2-1 series victory.

Two days later, Gen.G faced BRION, which had defeated them during the group stage of the 2025 LCK Cup. Despite a tumultuous early game, Gen.G secured a 2-0 sweep by dominating critical fights around Dragon and Baron, preserving their perfect record.

Meanwhile, Dplus KIA edged out Nongshim RedForce 2-1 on May 31 to remain in contention for the sixth and final spot in the Legend Group. RedForce had already guaranteed at least fifth place with a 2-0 win over T1 on May 30, highlighted by top laner Hwang "Kingen" Seong-hoon’s performances. KT Rolster rebounded from its loss to Gen.G with a 2-0 victory over DRX on May 31, but Dplus KIA’s win over RedForce on June 1 resulted in a tied record and identical set differential (+2) between Dplus KIA and KT Rolster. Both teams finished 10-8, necessitating a best-of-three tiebreaker on June 4 at 5 p.m. to determine who joins Gen.G, RedForce, T1, DRX and BRION in the Legend Group.