Wasps director of rugby Dai Young insists a place in next season's European Rugby Champions Cup beckons after Stade Francais were dispatched 30-29.
The first leg of the race to secure the 20th and final spot among Europe's elite reached a dramatic climax at Adams Park when a penalty by Andy Goode snatched victory as the final whistle blew.
Only seven minutes earlier centre Waisea Vuidravuwalu had accelerated between Elliot Daly and Andrea Masi to put Stade on the brink of victory, but Wasps replied with a desperate do-or-die assault that forced their opponents offside and Goode obliged from the kicking tee.
The second leg takes places in Paris on Saturday and - while the Aviva Premiership's play-off representatives have only a one-point lead to protect - Young believes they will also triumph at the Stade Jean-Bouin.
"I always felt we'd have to win both games to go through. I never felt we'd have a huge lead leaving Adams Park to go there and sit back on," Young said.
"It would be very dangerous to sit back against a team of their quality and hope they don't score too many points, because they will.
"We showed we can cause them problems in this leg so we'll go to them full of confidence and belief.
"We respect how good they are and how big a challenge it is, but this doesn't change anything because we always felt we'd have to go there and win.
"Beating them makes a difference to the psyche - we're 1-0 up.
"The players came into the dressing room with their heads down and I told them there's nothing to have your heads down about.
"They should be proud of that performance because we caused Stade lots of problems.
"We should have been going there with a 10-point lead, but that doesn't change the fact we can go there and win."