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A gripping showpiece was effectively sealed in the first period of extra-time when substitute John Kennedy lashed home a scintilating winner before receiving a second yellow card for celebrating wildly with the crowd, which saw him sent off.

But Boca also ended the game with 10 men when Frank Fabra was dismissed for violent conduct, slapping Fluminense captain Nino after a brain explosion just five minutes into the second period of extra-time in the wake of a failed penalty shout for his side.

It was only Fluminense's second second appearance in the final stage of the competition, and it went ahead on 36 minutes when Argentinean sharpshooter German Cano swept home to open the scoring. 

Boca clawed it back to 1-1 with a 72nd-minute long-range leveller from Luis Advincula, but it was John Kennedy who would have the last word for the Brazilian side.

The Rio club's triumph capped off an undefeated eight-game streak in the Libertadores, matching its longest unbeaten run from the previous year.