London - Ireland
The 30-year-old fly-half -- who knows the French game well having spent two seasons at Racing92 -- has won two successive Six Nations titles under Schmidt's stewardship and claimed some notable southern hemisphere scalps such as South Africa and Australia.
However, Sexton made his remarks the morning after the Irish received a salutary reminder that they are not the finished article yet as a spirited Italy gave them a few scares in Ireland's 16-9 victory on Sunday.
Ireland and France are on 14 points going into the game in Cardiff with the winners avoiding the Pool C number one team, likely to be New Zealand. The Pool D winners would still
"Yes we probably do need the best performance of Joe's time to win this weekend," said Sexton.
"We're in no doubt we'll be playing against the best French team that there can be, and we'll have to be at our very best to come out on top."
Sexton, who is returning to his Irish province Leinster following his French sojourn, said the France team at this World Cup is far different from the squad of recent Six Nations tournaments.
His words are borne out by the facts as France have reached three finals -- all losses -- and only failed to reach the last four on one occasion, in 1991, when England won an ill-tempered quarter-final in Paris.
"When it comes to a World Cup it's almost like they build for this, it's like they use players through the Six Nations year on year to have a big playing pool for the World Cup," said Sexton.
"And you can see from their previous results, how many semi-finals and finals they've been in.
"Arguably they should have won the last World Cup and they were in turmoil in the group stages.
"So we've got to be aware of all these things and realise them but at the same time we know we've got to concentrate on ourselves because if we get our performance right we can be a good team."
Sexton, who contributed 11 of his side's points in the Italy game and set up their only try to boot, admitted the performance on Sunday had left a lot to be desired.
"I don't know if it's a wake-up call I think we're a pretty grounded
"The ease with which they (Italy) were able to keep the ball and go wide-wide, if we let France do that it will be pretty tough.
"We dug deep, we won ugly and at times you have to do that," added Sexton, echoing Schmidt's mantra from Sunday.
Sexton, though, said he would put up with one poor performance -- against an admittedly vastly improved and more motivated Italy team than the one who had lost to France and then edged out Canada.
"I'd rather be sat here now with everything on the line against France rather than off the back of a defeat," said Sexton.
"We're where we wanted to be at the start of the tournament."