Dark Marik turned his Duel with Dark Yugi in the finals into a Shadow Game that gave him a clear edge; when Dark Yugi lost Life Points, Yugi Mutou's body would fade away, and when Dark Marik lost Life Points, the original Marik would fade away. While Dark Marik would survive if Marik didn't, if Dark Yugi lost, both he and Yugi would be destroyed. Discarding "Ra" on his first turn, Dark Marik helped Yugi get "Slifer the Sky Dragon" out so he could destroy it himself with "Ra", which he succeeded in doing with God Phoenix. He reclaimed his "Monster Reborn," giving Dark Yugi a last chance to draw. Dark Yugi didn't even look at the card before he Set it, but Dark Marik wasn't interested. He brought out "Ra" again, this time using its One Turn Kill effect to raise its ATK and prepared to attack. He also revealed that he had taken the Millennium Ring from Dark Bakura, revealing that he was behind Bakura's disappearance to the group at large. When Dark Marik attacked, Dark Yugi revealed the card Kaiba had given him - "Devil's Sanctuary," which forced Dark Marik to attack himself. Dark Marik was forced to use the "De-Fusion" that Dark Yugi had given him through "Exchange," seperating himself from "Ra" and boosting his Life Points.
Yugi then Summoned "The God of the Obelisk" and attacked Dark Marik directly, badly injuring him, but Dark Marik created a clone of it called "God Slime." He used the Slime to stall until he could revive "Ra" to destroy "Obelisk," with God Phoenix, but Dark Yugi prevented this by using "Slifer" as a shield. Dark Marik simply re-revived "Ra," and began to boost its ATK via One Turn Kill, only for Dark Yugi to sacrifice the "God Slime" to activate the effect of "Obelisk," boosting it to infinite ATK. Thanks to "Ra" being higher on the Divine Hierachy, Dark Marik blocked the attack, and prepared to finish Dark Yugi off, attacking "Obelisk." Dark Yugi responded with "Dimension Magic," that would destroy "Ra." Dark Marik, knowing that Dark Yugi didn't want to destroy the original, taunted him, claiming that Marik wouldn't survive the shock even with a single Life Point left. By this time, Rishid had woken up and made Marik realize that he had to accept his responsibility for being a Tomb Guardian and the death of his father. With this confidence, Marik overpowered his evil self and urged Dark Yugi to attack him. Dark Yugi did so, destroying "Ra." The shock of the monster's destruction while Dark Marik was fused to it allowed Marik to retake control, putting Dark Marik in the position of the sacrifice. Dark Marik begged his other self to work with him, but his efforts were in vain. Marik forfeited, reducing his Life Points to zero and destroying Dark Marik.