USG CEO Phillipe Bormans admits his team were blown away after a 3-0 defeat sent them spinning out of the Champions League qualifiers.
The Belgians struggled to cope as the Ibrox cauldron bubbled to a raging boil, pushing the players to their top levels.
The noise was off the charts and Rangers were rampant as goals from James Tavernier, Antonio Colak and Malik Tillman sealed passage to face PSV in a £40m, winner-takes-all shoot out.
And Bormas admits, he's never seen anything like it.
Speaking after the defeat, USG chief Bormans said: "Obviously we are disappointed, I think we have to be. We were close but we have to be honest too. It was deserved. They won, they started this match well from the first minute, with a bit of luck of course. If this first goal does not fall, we return to half-time at 0-0.
"But in the end, it's football, we have to stay correct. Today, we were under a pressure that we had never known. The speed of play was enormous. This team played in the Final of the Europa League a few months ago, it was seen.
"The first leg was also decided on details. We were the ones who showed what we are capable of. Tonight, we saw a team that has a budget that is much higher than ours. It was seen. Until the last moment, we fought. We were close."
Defender Siebe Van der Heyden was the man who gave away a crucial penalty just before half-time and he admitted such mistakes were the root cause of the defeat.
He said: "I tried to head the ball, missed it and unfortunately it came off my hand.
"We knew we couldn't make any individual mistakes because Rangers would punish them and that's exactly what happened. Organisationally, we were good in the game, but small individual mistakes are killing us. We were ready for Ibrox. But the atmosphere was incredible - you can't say anything else. But that shouldn't have been the decisive factor.
"And we missed a couple of chances too. If you don't convert them at this level, you get punished. Rangers are at a high level in Europe and we have taken them all the way. If you look at the bigger picture of where Union were two or three years ago, then we should be very proud."
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