With Lyon’s forwards tied into the maul Robson succeeded in sneaking over from short range.
Lyon finally turned pressure into points in the 35th minute with a successful penalty from 40 metres out on an angle from Berdeu.
Wasps took an 8-3 lead into half-time with Gopperth knocking over three points from the kicking tee.
The visitors started the second half like a house on fire with Tom Willis hitting a tremendous angle to charge into the Lyon 22. They lay siege to the Lyon line, but the defence remained intact.
Lyon hit back with arguably the best try scored in this season’s Challenge Cup.
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Former New Zealand centre Charlie Ngatai raced clear from deep inside his own half with the ball spread wide to both Baptiste Couilloud and Toby Arnold, who was brought down just outside the Wasps 22.
With the Wasps defence at sixes and sevens Guillaume Marchand’s pass put Berdeu over for a stunning try.
Berdeu converted his own try to push Lyon ahead, but Wasps regained the lead from Gopperth’s boot four minutes later.
But Lyon’s pack had the bit between their teeth with their forwards getting over the gainline with ease.
Former Saracens lock Joel Kpoku charged towards the line, with replacement hooker Charcosset eventually powering his way over from short range.
After missing two penalties Berdeu made it a two-score game with a successful penalty.
Wasps desperately tried to force their way back into the game and Dan Frost had a try disallowed after the television match official spotted Francois Hougaard knocking the ball forward in the lead-up.
Wasps set up a grandstand finish when Gopperth scored courtesy of a well-worked driving lineout.
The New Zealander kicked the conversion to make it 20-18 with four minutes remaining but it was a case of too little too late for Wasps.