Gareth Bale claimed he was denied a clear penalty as Real Madrid's Champions League hopes were left hanging in the balance after their stunning 2-0 defeat to Wolfsburg.
Bale had his appeal for a penalty waved away by Italian referee Gianluca Rocchi after Cristiano Ronaldo had a goal disallowed for offside in the second minute on Wednesday.
The Wales international cut in front of Luiz Gustavo and won the ball before he was bundled over inside the area.
It proved to be decisive as Ricardo Rodriguez and Maximilian Arnold scored within seven minutes of each other in the first half to lead Wolfsburg to a remarkable victory.
"I went down. I had the ball in front of me and he took me out, if that's outside the area it's a foul, so inside it has to be a penalty," Bale said.
"Obviously it's a frustrating result but we get another chance.
"It's not a good result, but we have time to turn it around. What we have to do is make sure we win the return leg by three goals."
Madrid, who had a six-game winning streak in all competitions snapped, head back to the Spanish capital for the second leg on April 12.