Harlequins gave themselves a lifeline in the Heineken Cup with their first win of this season's campaign.
Outside-half Nick Evans triggered a thrilling display with the first of his team's four tries in Nantes to claim a bonus-point win that lifts Harlequins from bottom of Pool Four to second, behind leaders Clermont-Auvergne.
And captain Easter, who scored the second try, admitted the scale of the victory against the big- spending French outfit had even taken Harlequins by surprise.
Easter said: "We didn't think it would go that well. We're not a results-orientated side, we just wanted to put a good performance out on the park.
"We like to play with intensity and we came close to doing that for the full 80 minutes here. But we know how tough this pool is and now we have to back it up next week.
"We have been slowly building since the last Heineken Cup game at Clermont and we have rediscovered ourselves and our verve."
Harlequins looked to be heading for an early exit from the tournament following defeats in the opening rounds to Scarlets and Clermont-Auvergne.
But they continued their run of winning results in the Aviva Premiership into Europe to claim a famous win at Stade de la Beaujoire.
Easter said: "We are backing each other all the time. Perhaps we got into a habit of losing.
"We like to play quite a high risk style of rugby so when things don't go well we weren't backing each other up.
"Now things are going well and our decision making of when to pass, when to offload or protect the ball, is much better.
"When you build that pressure, things start to happen and we have the players who can score, especially on a fast surface like we had here. Then you get a few wins under your belt and confidence soars."
It was a first defeat of the campaign for Racing Metro, who handed Mike Phillips a debut off the bench, and raises questions over the decision to move this home tie 240 miles west to Nantes.
Head coach Laurent Travers said: "The performance was just not good enough.
"Too many players did not play the way we expect and you cannot do that in this competition. We are very disappointed."