Real Madrid coach Carlo Ancelotti struggled to explain how his side were shocked 2-1 at home by rank outsiders Sheriff Tiraspol in the Champions League after dominating the match.
Luxembourg midfielder Sebastien Thill scored an outstanding late half volley to snatch an unlikely victory for Sheriff, who reached the Champions League group stage for the first time this season after winning four qualifying rounds.
Sheriff took the lead against the run of play with a header from Jasurbek Yakhshiboev while Karim Benzema equalised for the 13-times European champions with a second-half penalty before Thill secured the victory.
Real had 30 shots on goal and 11 on target while keeping 67 per cent of possession and winning 13 corners while the Moldovan side had only four attempts, scoring two of their three shots on target and failing to win a single corner.
"Everything went well for them while everything we did turned out badly," Ancelotti said after his side's first defeat of the season.
"More than worried we are sad. We played with intensity and commitment but lost due to the finest details. The team played well, we could have been sharper in the area but it's difficult to explain what happened.
"The small details cost us the game and we should learn from that in the future. A corner kick, a stupid foul - they cost you and now we talk about a defeat we didn't deserve.
"We've missed out on three points and the group is wide open. We need to win our next game."
Sheriff, who were founded in 1997, are top of Group D with six points, after beating Shakhtar Donetsk 2-0 in their opening game.
"I dreamed of winning in the Bernabeu, I have always followed Madrid they are the most successful team in the Champions League so to beat them at home is a huge achievement," said Sheriff defender Gustavo Dulanto.
"There's still a long way to go and we can't relax because there's no logic in football, as today's result shows. We came here with the knife between our teeth but we can only look forward to the next game."
Captain Frank Castaneda revealed his side had fancied their chances before kickoff.
"We knew we could win here and before the game we had it in our heads that we could and as captain I tried to motivate the team and tell them we could do it because this is football," he said.
"Real Madrid is an historic team but on the pitch it's 11 players versus 11 and we came here to get the victory and got it.
"We are dreaming of getting into the last 16 and that's our objective. Our attention now turns to Inter and we'll work hard in order to ensure we keep getting positive results.
"Thill's goal is out of this world. It's one you dream of. I thanked him at the end of the game."
Match-winner Thill added: "We're so happy today. We played a really good game. The side were so brave with how we played and luckily enough I was able to score a bit of a stunner."