The Manchester City star was part of the team who earned a 4-0 victory over the Brazilian side in Saudi Arabia to claim their fifth trophy of 2023.
While clearly an occasion of celebration, the England defender found himself involved in an altercation with the 40-year-old midfielder.
After being pushed by Melo, Walker had to be held back by his teammates and Man City's backroom team to ensure that the celebratory occasion didn't turn sour.
Frustrations had been boiling over for Fluminense during the second half of the contest, largely due to Man City's dominance.
This included a rash challenge on midfielder Rodri, leading to him hobbling off the pitch in concerning scenes.
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However it was Julian Alvarez and Phil Foden who were the stars of the show, providing three of the four goals - alongside an own goal from Nino - to officially see Man City crowned as the best side in world football.
That trophy is City's second of the season so far following their UEFA Super Cup win, but with the Premier League, FA Cup and Champions League still to play for, the Blues will be desperate to add another impressive haul to their trophy cabinet during the second half of the season.