France's Guilhem Guirado gestures to the crowd following their Rugby World Cup Pool C game against Tonga at Kumamoto Stadium on Sunday. Photo: Aaron Favila/AP

KUMAMOTO  Frustrated coach Jacques Brunel said France could only improve ahead of their blockbuster Pool C clash against England after surviving a big scare against Tonga to stumble into the World Cup quarter-finals on Sunday.

Just as in their opener against Argentina, France held on for a nerve-jangling 23-21 win, having built a big lead in the first half before seeing it frittered away after the break at Kumamoto Stadium.

The result left France second in the pool behind unbeaten England, and the northern hemisphere rivals will play off for top spot when they meet in Yokohama on Saturday.

While France have shone only in patches in all three of their pool games, which included a laboured 33-9 win over the United States, Brunel said he was not alarmed.

"I'm not worried but unsatisfied. The players are frustrated. They attacked the game well and had good opportunities to score in the first half.

"But they made mistakes by rushing and by poor handling. We had wanted to play a better game. There is still work to do."

The Fijian flair of winger Alivereti Raka and centre Virimi Vakatawa shone during the balmy twilight match, with each scoring first-half tries and repeatedly combining to menace the Tongan defence.

After the break, however, France had two tries cancelled on review by the TMO and could rely only on two penalties from young flyhalf Romain Ntamack to hold on as Tonga came roaring back with a try by centre Malietoa Hingano and the last-gasp five-pointer to flanker Zane Kapeli.

France will face the true test of their level when they take on Eddie Jones's England in "Le Crunch", and captain Jefferson Poirot, their third skipper in Japan, said they would be working to improve their scrums after struggling against the Tongan pack.

"Today, our scrums didn't let us do what we wanted. We couldn't attack from the scrum. We need to work on it," the prop said.

"The game against England is important as preparation for the quarter-finals. Whether it's Australia or Wales (in the quarter-finals), the two will offer us the same intensity as the English.

"(England's) a match on which we'll gauge our progress. As a Frenchman, I love to play England."

Reuters