Lawrence Dallaglio was left disappointed as Wasps crashed to a 37-27 Heineken Cup defeat to Clermont Auvergne in France.
The defending Heineken Cup champions conceded a last-minute try to lose a valuable bonus point in the Parc des Sports Marcel-Michelin.
Mario Ledesma's try on the stroke of half-time proved to be the main talking point as Television Match Official David McHugh awarded the score even though replays proved his grounding of the ball was inconclusive.
And Wasps captain Dallaglio said: 'We were sloppy in the first half and those tries we conceded were very easy and I'm really disappointed with that.
'What I think about the Ledesma try is irrelevant but it goes both ways. Sometimes you get those decisions and sometimes it goes to the opposition.
'But I was more disappointed with the way we gave away those tries. All credit to the lads for the way we came back in the second half.
'Now, It sets up the match next week nicely and it will be a real contest.
'This is a really tough pool and I'm disappointed we've not managed to pick up a bonus point.
'But now we have to do the business at home next week.'
Clermont Auvergne captain Aurelien Rougerie could not hide his delight after the wing powered over for the last-minute try to deny Wasps a crucial bonus point.
The star-studded French outfit bounced back from a heavy 36-13 defeat to Munster to maintain their 100% home form in Europe this season by grabbing the Pool 5 win in dreadful conditions.
And now Clermont travel to England next Saturday for the return fixture against Ian McGeechan's side in confident mood.
Rougerie said: 'This was a very difficult match for us but to get the try at the end to prevent Wasps a losing bonus point was fantastic.
'We want to make sure we keep going in the right direction and we know we've got a number of things to work on and improve. The game in England against Wasps next week will be very tough for us.
'But for us the symbol of beating the European champions is fantastic. But we also know we need to keep our feet on the ground.'
After trailing by 20-10 at half-time, Wasps had staged an impressive comeback and tries for Tim Payne and James Haskell - the flanker’s second of the game - put McGeechan's side 24-23 ahead after 50 minutes.
However, Clermont fly-half Brock James was immaculate in his kicking, and his four second-half penalties left Wasps trailing 34-32 with eight minutes left on the clock.
Danny Cipriani held his nerve to kick a long penalty and put Wasps back into contention for a bonus point just two minutes later, and when Tom Voyce kicked for the corner with one minute left to play, Wasps supporters may have dared to think an historic win was within reach.
However the line-out was not cleanly taken, and although Wasps kept possession and the ball in hand, they were forced back into their own half.
When the ball rolled out of the back of a ruck, Clermont pounced and spun the ball wide for their captain Rougerie to go over in the corner and snatch a five-point win for his team.