PARIS, May 2: France's presidential rivals, right-winger Nicolas Sarkozy and socialist Segolene Royal, on Wednesday hold a face-to-face television debate that could seal their fate in Sunday’s decisive vote.

More than half the country’s adult population was expected to watch the two hour confrontation, which was to be carried live on France's two biggest television channels.

Televised debates have been held between the finalists in every French election since 1974 -- except in 2002 when Jacques Chirac refused to meet far-right leader Jean-Marie Le Pen.

Both the Sarkozy and Royal camps know that the head-to-head encounter could be crucial in determining the choice of millions of uncommitted voters.

Nearly seven million people chose defeated centrist Francois Bayrou in the first round of the vote on April 22, and the second-round campaign has focused on capturing his electorate.

Francois Hollande, head of the Socialist Party (PS) and Royal's partner, said the debate would be the “most important ... since 1981” when Francois Mitterrand beat incumbent president Valery Giscard d'Estaing.

Giscard d'Estaing, who took part in two televised debates with Mitterrand in 1974 and 1981, said the head-to-head between Sarkozy and Royal would be the “decisive ... high-point of the campaign”.

In the 1974 debate Giscard d'Estaing coined the phrase “You do not have a monopoly on the heart”, which was seen as giving him the edge. He went on to win by a very small majority.

However Sarkozy, who heads the ruling Union for a Popular Movement (UMP), sought to play down the significance. “I don't think that the French are going to make their choice of president for the next five years based on an impression from a two-hour debate,” he said.

Leading by between two and eight percentage points in opinion polls, Sarkozy needs just to hold his own and make sure he does not lose his temper, according to Christophe Barbier, editor of L'Express news magazine.

“As for Royal, she is the outsider. She needs to make up some two million votes. So she will go on the offensive. She will attack Sarkozy for his record in office and accuse him of being a dangerous representative of the hard right,” he said.

After long discussion, the two camps agreed on the rules of the debate, which will start with general questions about France and its institutions, moving on to social and economic issues, followed by education, research and the environment, and concluding with international questions.

It will be chaired by the country's two best-known news presenters, with the candidates facing each other over a two-metre (six-foot) table. Speaking time will be closely monitored to ensure each has a fair share.

Sarkozy and Royal have both prepared extensively for the challenge, viewing clips of their adversary, and studying briefing papers on their weak points and practising dummy runs with aides.

The two have faced each other only once before in a debate. Just before the 1993 legislative elections they had an ill-tempered exchange in a television studio, a clip of which has been circulating on the Internet.—AFP