Servette keeper Joel Mall admitted they wilted at Ibrox initially because of the 'insane' atmosphere before battling back strongly.
Rangers will take a narrow 2-1 lead to Switzerland at Servette's Stade de Geneve, which they have sold out for the first time in 20 years.
Cypriot keeper Mall made a string of saves to keep his side in the tie with Servette again being reduced to ten men following the second booking of David Douline, who also conceded an early penalty.
But they got to a nightmare start after going two goals down in the first 15 minutes.
And Mall admitted they froze in the Ibrox cauldron.
He said: "We should have started the match better, without giving away a penalty.
"It was very difficult to play at first because of the insane atmosphere in the stadium. It was amazing.
"But I think we recovered well.
"I believe we have to be satisfied with that result because we only had ten men for a long spell in the match."
Meanwhile, Servette stopper Steve Rouiller has declared himself fit for the return leg despite being carried off at the end of the match at Ibrox following a head clash that left him requiring five stitches.
He said: "I will be available for next week.
"In the end, a 2-1 defeat here in the circumstances was a positive result.
"After we scored the penalty, I thought we defended very well and were very disciplined.
"It was backs to the wall, but we were solid. Although we had to thank our goalkeeper for making a few saves.
"He's kept us alive for the second leg and we all can't wait for it.
"However, we still have to realise this is an extremely high level we are playing and it will be difficult to qualify."