Sarkozy had consistently trailed Socialist candidate Francois Hollande in the race, but the tide appeared to change late this week in the wake of Wednesday's nationally televised debate between the two.
Britain's The Guardian said Saturday Hollande remains the front-runner but has lost his double-digit lead in the polls and urged his supporters Friday not to take victory for granted.
"I don't want to be a killjoy, but don't make what could be the fatal mistake of thinking that the game is already over," he said. "I have to tell you that I am sure of nothing."
Although the reasons for Sarkozy's late gains were unclear, The Guardian noted Hollande has been successfully painting the incumbent as a pal of the upper crust while he is more of a man of the people.
The newspaper said Socialists in Paris predicted a big celebration at the famed Bastille should Hollande win Saturday.
"If Hollande wins, people will automatically gravitate towards the Bastille without even being told," one member of the Socialist Party said. "The place is very symbolic and it would be perfectly natural to celebrate victory there ... if we win, that is."