London Wasps director of rugby Dai Young credited his team following their dominant performance in a 47-7 win over Grenoble.
The French outfit most recently defeated Toulouse at home in the Top 14, but were blown away by the Aviva Premiership outfit on Saturday.
"We were outstanding tonight. I certainly wouldn't have put money on us coming out here and beating them by 40 points," Young told the Wasps website.
"They are hard to beat at home but we were on top all night. The pack were outstanding early doors and the backs really spread the ball really well and stretched them. I was pleased with one and all.
"We had a great attitude to back up the win last week and I couldn't have asked for any more from them.
Guy Thompson and Charlie Hayter both scored two tries each in the heavy victory that moves Wasps four points clear at the top of Pool 4.
"We had periods where we defended for a while but we kept out shape really well. When we had chances we were clinical and they only looked threatening from a few of our mistakes," added Young.
"We have to back it up next week at home and realise the job isn't done. We need to push for a five point win next weekend.
"The two seasons I have been here we have qualified out of our groups and we want to keep moving forward and we are determined as a group to come out of this pool on top."