Real Madrid midfielder Federico Valverde appeared to mock Barcelona legend Lionel Messi after scoring the winner in Wednesday's El Classico.
The Uruguay international finished off a stunning counter-attacking move to send Carlo Ancelotti's side into the Spanish Super Cup final with a 3-2 triumph.
After converting the 98th-minute winner in extra-time, Valverde whipped off his shirt and showed his No15 jersey to the spectators in Riyadh, Saudi Arabia.
Barcelona icon Messi famously did the same in April 2017 after scoring a 92nd-minute winner against Real at the Bernabeu.
The capital club will now face Atletico Madrid or Athletic Bilbao in the final of the four-team competition, which takes place on Sunday.
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But it's another blow for Barcelona, who have already been knocked out of the Champions League and won't catch Real in the La Liga title race.
The Catalan giants are currently sixth in the table - 17 points behind Real - and their hopes of winning silverware this season rest on the Copa del Rey and Europa League.
"I'm sad and upset because the game was there for the taking," insisted Barcelona manager Xavi after the game.
"We had a bit of a complex at the start but once we got over that I think we were better than Madrid. We took a lot of risks but that is the right path for us to become competitive.
"We can be proud. We are on the right path. But I'm sad because we wanted to be in the final. I'm not upset about the performance though.
"It was our errors that let us down. We have to be more responsible with the ball and we did not deal with the counter attacks. But we will grow from this. We can compete with anyone."
It was a thrilling semi-final between the two giants of Spanish football, as Real ace Vinicius Junior opened the scoring in the 25th minute.
Luuk de Jong equalised for Barcelona just before the interval, but Karim Benzema restored Real's advantage midway through the second half.
Emerging talent Ansu Fati's late equaliser forced the game into extra-time, giving Valverde the chance to be the hero in Riyadh.
"We were aware that it was going to be a very close encounter, and it turned out that way," said Real manager Ancelotti after the game.
"We played well, particularly in the first half. In the second half we played very well on the counter-attack and in the end tiredness kicked in.
"It was an entertaining match and I think we put on a good show and gave a good account for Spanish football.
"Anyone could have won as two different styles of football came up against each other. They focused more on possession and we played on the counter-attack.
"We deserved to take the lead in the first half but the second half was more evenly matched. We defended deeper to take advantage of the counter-attack, which proved to be very effective.
"We found some quality moves on the counter and scored three fantastic goals."