Turkish chef and restauranteur Salt Bae was on the pitch after Argentina's World Cup win over France in Qatar.
The celebrity chef, whose real name is Nusret Gökçe, appeared among the players and coaching staff, but it was unclear who let him onto the pitch to join Lionel Messi and his teammates on Sunday night for the celebrations.
Salt Bae has since been criticised for embedding himself with the Argentinian team.
He was also seen grabbing Messi repeatedly by the arm to get a word with him.
In the end, Messi posed for a photo with the chef, which Salt Bae posted on his Instagram account.
Salt Bae gained popularity five years for pouring salt on a steak.
Salt Bae was also pictured with the World Cup trophy, which is a violation of Fifa rules about who is allowed to handle it.
Salt Bae also posted a video on his Instagram account of him holding the trophy beside Argentinian goalscorer Angel Di Maria.
He then gave the cup a slap when handing it back to the player.
Salt Bae was also seen biting an Argentina player's winning medal.
He has posted pictures on his Instagram account of his time at the World Cup in Qatar, and was photographed with Fifa president Gianni Infantino.
Rules about who can touch trophy
Fifa rules state that the original solid gold trophy "can only be touched and held by a very select group of people, which includes former winners of the Fifa World Cup and heads of state".
There was a similar controversy in 2014 when the World Cup winning German team were pictured with singer Rihanna.
She was allowed to hold the trophy in a post-match party.
She tweeted at the time: "I touched the cup, held the cup, kissed the cup, took a selfie wit the cup."
Commenters online questioned Salt Bae's presence on the pitch, as he is not even Argentinian or a footballing personnel.
They also questioned why he was allowed to hold and pose with the World Cup trophy.
One person wrote on Instagram: "I thought only world champions could touch the cup?"
Top photos via Salt Bae