PARIS, April 9 (Xinhua) -- Jean-Luc Melenchon, hard-left candidate, with an anti-capitalist campaign, has gained momentum as a survey predicted him to seize the third place in the presidential election first round, for the first time eclipsing conservative challenger Francois Fillon.

A poll for Kantar Sofres published on Sunday showed Melenchon improved his score with six percentage points to 18 percent of voting intention, ahead of the right-center candidate Francois Fillon whose support was at 17 percent.

The front-runners far-right leader Marine Le Pen and independent contender Emmanuel Macron were seen neck-and neck with 24 percent.

Melenchon on Sunday addressed tens of thousands of supporters in the southern city of Marseille in a meeting which he described as a "magnificent demonstration of strength."

"It's heard, it's felt : victory is within reach of our efforts," he said.

Eleven candidates are officially competing to book a ticket to occupy the Elysee Palace in this year's presidential elections.

If no contender wins a majority of votes in the first round set for April 23, the top-score nominees will meet two weeks later for a run-off.