The flanker's first try for Wales helped them fight back from 12-0 down to complete a dramatic 20-19 quarter-final win and set up a last-four clash with two-time champions South Africa in Yokohama on Sunday (October 27).
He was also instrumental in a key part of the game, as France were reduced to 14 men after lock Sebastien Vahaamahina was sent off for elbowing him in the face.
But he followed the lead of captain Alun Wyn Jones in insisting the champagne would stay on ice despite reaching the semi-finals for the first time since losing to France in 2011.
"There is no celebration yet as Alun Wyn said," Wainwright told reporters.
"We haven't got the job done. The celebrations will come after we come away with the trophy."
France were on top at 19-10 in Oita on Sunday (October 20) when Vahaamahina's moment of madness left Les Bleus a man down with more than half an hour to play.
Wales still left it late, taking until six minutes from the finish to edge ahead for the only time in the match when replacement forward Ross Moriarty's converted try gave them a one-point lead.
Recalling the incident that eventually saw experienced South African referee Jaco Peyper show Vahaamahina a red card, Wainwright said: "It was a maul, and he had me by the neck to start with.
"I was trying to get the referee's attention, and then the elbow came in.
"I was a bit surprised the referee didn't see it to start off with, but thankfully the television match official pulled it up and it was dealt with. We put the pressure on afterwards and saw the game through.
"I am fine at the moment. It wasn't that nice at the time."
As for his try, the 22-year-old said: "The ball popped up and I can't really remember what happened apart from sprinting towards the line.
"It is a massive achievement for the team. It's great to come away with the win and look forward to the semi-final and eyes on the final as well."
Wainwright, who cuts a distinctive figure on the field thanks to a moustache, marked his try with an unusual stag impression and explained the gesture to reporters.
"I've got a sevens team back home called The Stags, so that was what the celebration was about.
"With the moustache, all my mates went to Prague on a boys' holiday and said they were going to grow moustaches."
Wainwright added: "They said if I grew one they would crop me into the photographs just so I didn't feel like I was missing out.
"I certainly don't feel like I am missing out now, being here."