PARIS (Reuters) - Former French prime minister Francois Fillon was seen as the winner of a final debate before a vote on who gets the conservatives’ candidacy in next year’s presidential election, a poll showed, in a fresh upset for favourite Alain Juppe.

French politician Francois Fillon attends the third prime-time televised debate for the French center-right presidential primary in Paris, France, November 17, 2016. REUTERS/Christphe Archambault/Pool

Juppe, 71, has for months been ahead in polls. But he has been struggling to fire up voters and has this week been losing some ground to his chief rival, former president Nicolas Sarkozy, and Fillon.

Whoever wins the two-round primaries on Nov. 20 and Nov. 27 has a strong chance of becoming France’s next president because of the divisions of the Left and persisting opposition among a majority of voters to see the far-right in power.

Fillon, who has seen his ratings suddenly start rising one week ago, was perceived as the most convincing by 39 percent of conservative and center-right voters who watched the debate on Thursday evening, versus 26 percent for Sarkozy and 25 percent for Juppe.

Minutes before the flash survey by Elabe pollsters was published, Fillon, whom polls had seen lagging for months far behind Juppe and Sarkozy, had urged voters to challenge expectations.

“The French are proud and don’t like to be told what to do,” he said. “Don’t be afraid to contradict opinion polls and the media that had decided it all for you ... Vote for what you believe in.”

Fillon was still ahead among all viewers independently of their political stripe but by a much narrower margin of 33 percent versus 32 for Juppe. Sarkozy, a divisive figure hated by many on the Left was seen winning by only 18 percent.

The poll was carried out only amid 1,012 voters who watched the debate.

A social conservative with economically liberal ideas who admires late British Prime Minister Margaret Thatcher, Fillon, 62, was Sarkozy’s prime minister during his five years as president in 2007-12.

In the overall uneventful and sometimes messy TV debate on France 2 television, Juppe and Sarkozy touted their experience in power and urged voters to rally behind them.

“I’m asking you to go vote en masse on Sunday,” Juppe said in his concluding remarks. “Together we’ll once more be proud to be French!”

Sarkozy, who has campaigned on a hardline law-and-order platform, has somehow narrowed the gap with Juppe over the past week. “The world as it is evolving will do France no favours,” he told the debate. “I want to protect it.”

Two much more comprehensive polls published on Thursday ahead of the debate showed Juppe winning the primaries but with a much narrower margin than in previous surveys. [L8N1DI3IF]

Anybody can take part in the primaries, the first such vote to choose a conservative candidate in a French presidential election, making it hard to identify who will vote and who will win.

The presidential election takes place on April 23 and May 7.

Polls have for months shown far-right leader Marine Le Pen emerging as one of the top two candidates in the first round but losing the second-round run-off.

Socialist President Francois Hollande’s deep unpopularity and the divisions of the Left mean polls forecast they won’t feature in the two-person run-off and that whoever wins the conservative primaries will face Le Pen and beat her.

Following the unexpected victories of Donald Trump in the United States and the UK vote to leave the European Union, polls in France are increasingly being taken with a grain of salt.