Kumamoto - French celebrations at reaching the World Cup quarter-finals were short-lived Sunday as coach Jacques Brunel rattled off a list of shortcomings to be addressed before they play England next weekend.
It took three penalties from Romain Ntamack to stave off a willing Tonga as France scraped home 23-21 in their Pool C encounter in Kumamoto, with Brunel saying he was happy with the final scoreline but not the execution.
The outcome of their clash with the also unbeaten England in Yokohama next Saturday will determine who Les Bleus meet in the first knockout match, likely to be either Wales or Australia.
"We want to play better so we need to train more," said the exasperated Brunel after France conceded 22 turnovers.
"We wanted a bigger scoreline but because of handling errors we were not able to achieve that. Therefore, I guess, we need to go back to basics.
"We tried many different things which didn't work."
Brunel also defended his player rotation, having changed his combinations in all three games against Argentina, the United States and Tonga, although he admitted there were problems at both set-piece and open play.
After a blitz start, France led 17-0 after 32 minutes but their moments of finesse were interspersed with unforced errors which the Tongans were quick to capitalise on.
They closed the margin to 17-14 early in the second half before Ntamack penalties stretched the margin to 23-14 leading to a cliffhanger finish.
A converted try put Tonga within two points with a minute left to play but they were unable to reclaim the ball at the restart and France were only too pleased to kick the ball into touch.
While France struggled for their victory, England beat the Pacific islanders 35-3, leading Tongan coach Toutai Kefu to depart from normal post-match diplomacy to suggest the inconsistent French may have trouble next weekend.
"England are very fit, direct and much more physical than the French team," he said.
"France obviously have that flair and good footwork out wide but with the French you don't know who is going to turn up. After we let in a couple of tries they could have gone on and scored another three or four."
Tonga, who picked up a bonus point for the narrow loss, outscored France three tries to two.