Irish ace Sam Bennett won stage 1 of Paris-Nice on Sunday by timing a late surge to perfection in a mass bunch sprint.

It was a fourth stage win on this race for Bennett as he surged past 2019 world champion Mads Pedersen in second while Frenchman Arnaud Demare came third after his lead out man fell during the run-in of the 166km stage.

"It was chaotic at the end there, as the road got narrow," said Bennett, who won two stages of last month's UAE Tour.

"I got into the right position with 1km to go and just stayed calm and made my move 150m out."

The 30-year-old sprinter leads the overall standings from Demare by four seconds, and will go into stage two wearing the yellow jersey.

Bennett's power left his rivals trailing and with two more sprints expected on the eight-day run to Nice the 2020 Tour de France sprint jersey winner appears even stronger this season.

French champion Demare said it was a hard day of racing.

"It might not have looked like it, but that was a fast last 50km, but I was quite happy with my race," said the FDJ leader.

There was bad news for Ineos as Richie Porte fell with 30km to go and pulled out on stage 1 of his first race on his return to Dave Brailsford's team.

Dropped bottle ends Porte's Ineos debut

Ineos rider Ben Swift said Porte had fallen victim to a dropped water battle, just as Geraint Thomas had at the 2020 Giro.

"As we started to go (up a climb) someone drops a bottle, George Bennett hit it, turned left into Richie, and then it just took Richie's front wheel out," Swift said in a video Ineos posted on Twitter.

The accident means Giro d'Italia champion Tao Geoghegan Hart, who finished with the main pack on Sunday, will take sole leadership of Ineos for this race, as he prepares for the Tour de France in June.

Porte's fellow Australian Michael Matthews won five seconds of bonus points in the two intermediate sprints and ended the day third in the overall standings despite getting caught behind the fall in the final dash for the line.

On a cold sunny day there were plenty of roadside fans out in support, especially as the race covered the same 50km loop twice in the final part of proceedings.

Monday's second stage is a 188km run from Oinville-sur-Montcient outside Paris towards Amilly as the 1,207km event known as 'the Race to the Sun' begins its long slog South.

Paris-Nice tries to roll all the challenges of a Grand Tour into eight testing stages and is an early marker of who is hot and who is not.

Tuesday's individual time-trial should shake up the overall standings.

But there are also 27 climbs, including a Saturday showdown on the Colmiane mountain in the Nice back-country, before Sunday's potential decider with a major climb on the short run into Nice itself.

Slovenian Primoz Roglic is the race favourite and finished safely in tha main pack Sunday.