A World Cup-winning star looks unrecognisable following an end-of season a dye-job.
And fans were quick to draw comparisons between the player and one of his club team-mates.
The Argentine was seen in Atletico training showcasing his signature buzzcut, albeit this time dyed bright blue and accompanied by a black heart on the side of his head.
The trim was a nod to French forward Antoine Griezmann who sported a similar bright green number earlier this year.
Griezmann rocked a pink heart rather than a black one.
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The player in question is Rodrigo de Paul - a key man in Lionel Scaloni's men's triumph.
Unfortunately for De Paul, he was unable to showcase the new look in Atletico's final game of the season against Villareal.
The midfielder did not make the Atletico squad after picking up an injury.
The two sides played out a dramatic 2-2 draw with Villareal bagging a last minute equaliser through Jorge Pascual.
Atletico secured Champions League football, finishing third in LaLiga.
The draw saw Atleti finish one point behind city rivals Real Madrid.
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Atletico needed to better Madrid's result to finish second in the LaLiga table but couldn't squeeze past Villareal despite Real drawing 1-1 with Athletic Club.
Despite not being able to help his team in the final game of the season, it has been a fine personal season for De Paul.
During the World Cup, he earned the nickname Messi's 'bodyguard' for snapping into tackles with any opponent that fouled or dispossessed the Argentine captain.
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De Paul played all seven of Argentina's World Cup games as La Albiceleste secured their first World Cup victory since 1986.