Julián Álvarez was whistled by Atlético Madrid fans as the wantaway forward made his first appearance of the season in his team's 2-2 draw with Villarreal on Sunday.
Marc Pubill put Atletico ahead at the Metropolitano and Gerard Moreno levelled from the penalty spot, before defender Robin Le Normand was sent off, leaving Atlético with 10 men.
The visitors went ahead through another penalty, converted by Georges Mikautadze, before Giuliano Simeone made it 2-2 late on.
Álvarez's name was loudly whistled by fans when it was announced among the Atlético substitutes pre-match, and again when he was introduced in the 66th minute, with the home side chasing all three points.
At full-time, as his teammates stayed on the pitch to applaud Atlético's fans, Álvarez headed alone down the tunnel, as he was targeted by more whistles.
"I think we have to all be united," goalkeeper Jan Oblak told DAZN. "Julian is here, he's with us in the team, and while he's with us, we'll support him.
"We know what he can do, what he can bring. It isn't comfortable for anyone, but let's hope it's all resolved, and at the end of the season we can all be happy."
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"We're adapting to the situation we have," coach Diego Simeone told DAZN. "What's clear to me is that to win trophies we need a centre-forward. While a player is here at the club, we're with them to the death."
"The club decided that he [Álvarez] shouldn't go up to the stands, and the fans," Simeone explained later, in his post-match news conference, when asked about Álvarez leaving the field before his teammates.
"It was the club's decision to keep him away, and get him to the dressing room. It's not for me to give advice. I have to focus on my job... I won't answer every question about Julián."
Atlético CEO Miguel Ángel Gil Marín said on Friday that Álvarez "hasn't had the best advisors" as he has sought to push through a move to Barcelona this summer.
Álvarez made public his desire to leave during the World Cup, but Atlético rejected bids from both Barça and Real Madrid.