Movement (UMP) Jan 14, polls showed the two rivals running neck and neck, with each receiving 50 percent of the vote.
But Royal, who was named the Socialist Party nominee seven weeks earlier, decided to begin her campaign with an exercise she called "participatory democracy," travelling around the country to engage in discussions with voters before formulating her platform.
Although well intentioned, it was a naive and ultimately fatal move, for it made her appear tentative and without ideas of her own. And it left the media field open for Sarkozy, who took full advantage of it by presenting himself as a strong, decisive leader with a well-thought-out programme for governing.
Royal fell behind in the polls immediately. When she finally presented her platform in mid-February, it was too late: she had allowed Sarkozy to snatch the initiative and never caught up in the polls. And she never managed to erase the initial image her first few faltering steps into the campaign had created.
Surveys throughout the campaign showed that a majority of French voters preferred her platform to Sarkozy's, but an even larger majority found him to be more "presidential" - that is, strong, confident, competent and knowledgeable.
When finally, in last Wednesday's televised debate, Royal attempted to correct her image by going on the offensive against her opponent and by trying to appear confident and assertive, to many voters it seemed transparent and insincere. And it came far too late in the day to be of any help.
In addition, as in 2002, when Socialist candidate Lionel Jospin did not even make it to the runoff vote, Royal did not understand that insecurity was a main concern of the French.
But unlike five years ago, when the issue was crime in the streets, today French fears involve social issues: unemployment, purchasing power and inequality - in other words, the traditional bread-and-butter issues of the Socialist Party.
In wanting to present herself as a new kind of Socialist, Royal took too long to address these concerns and underestimated their importance to the French electorate.
Sarkozy also managed, far better than Royal, to recognise and address the deep conservatism of the French. A revealing poll, made public by the TNS-Sofres institute in mid-April, underscored just how deep that conservatism runs.
Of the 1,500 people who responded to the poll, 57 percent said they wanted "a society with more order and authority," while only 37 percent preferred a society "with more individual liberties".
Sarkozy's calls for harsher penalties against repeat juvenile offenders, his proposal for the creation of a ministry for immigration and national identity and his vow to erase the heritage of the May 1968 student and worker unrest, which he said was responsible for the decline of morals and authority in France, all addressed that conservatism.
Finally, Sarkozy managed the difficult trick of embodying both stability and change, for he was also the candidate preferred by those who believe that the French state and economy must be thoroughly reformed and modernised.
It was an impressive campaign performance by Sarkozy and his team. And the French who voted for him are hoping that this professionalism will carry over into his mandate, which begins on May 16.