REAL MADRID'S team bus was attacked with bottles as it arrived for their Copa del Rey quarter-final clash against Athletic Bilbao.
As the bus arrived at the Bilbao's stadium it was pelted with bottles and other objects.
A window was also left smashed by the violent crowd.
The Basque-based club later issued a statement, saying: "Athletic regrets and condemns the incidents that occurred upon the arrival of the Real Madrid bus, to which it has already personally apologized."
The intimidation must have worked as Bilbao saw off the league leaders with a late strike by Alex Berenguer.
Berenguer unleashed a sweet left-footed strike, beating keeper Thibaut Courtois, and firing Bilbao into the semi-finals.
Bilbao's victory was full deserved, with the visitors only managing to muster two shots in target all game.
Real were, however, without main man Karim Benzema who missed the fixture through injury.
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Carlo Ancelotti snubbed the opportunity to bring Eden Hazard on late on to try and swing the tie in Real's favour, seemingly much to Gareth Bale's amusement.
The Italian instead opted for teenager Eduardo Camavinga to replace Toni Kroos.
Ancelotti hopes the loss will make his team stronger as they look to secure the tightly-contested LaLiga title.
On the loss, he said: "We're hurt because we want to win everything. I don't think it will have consequences. I only hope that it makes us stronger.
"We don't have players of Karim's quality. We didn't change the plan. We tried to play from the back, and we couldn't. Athletic's pressing was really great until the 70th minute.
"I think in extra time we would have had the advantage, but they scored in the last minute. We played too much on the wings. We should have used [David] Alaba and Casemiro more. It didn't go the way we wanted.
"It's not the worst game of the season. It was even until the end. I'm not surprised with how the game went."