Real Madrid captain Sergio Ramos felt his side should have been awarded two penalties and questioned why the Video Assistant Referee was not used against Barcelona.
In the first El Clasico of the season, Los Blancos managed to secure a point at the Nou Camp on Wednesday evening although they remain second on the log.
VAR has been in the headlines across Europe's top five leagues this season, but Ramos was surprised the technology was not used for the visitors' penalty appeals.
"We saw them at the break and they look pretty clear. They're both penalties, but we can't change that now," Ramos told Movistar.
"VAR is here to help. It's bad luck. On another day, it'll be our turn to have a penalty that they don't check."
Ramos did have some praise for the Los Blancos side, despite only picking up a point.
"You can't be happy when you don't win, but getting something here is always positive," he said.
"We saw a great Real Madrid today, with a lot of personality, on a very tough pitch. We went to steal the ball, which helped us create many chances. There were few mistakes and that's the end result.
"We controlled the game quite well. We had more chances than them. It's not easy to get the ball off them. The strategy of pressing high worked well.
"We're going through a great dynamic in terms of play and we're also good physically. It's a shame the year is ending - we'd like this not to stop.
"Now, we have Athletic and hopefully we'll continue like this after the holidays."