Belgium's Tom Boonen snatched the first stage of the Paris-Nice cycle race over 186.5 kilometres.
Belgian Tom Boonen celebrates winning the first stage of the Paris/Nice race
Boonen out-sprinted Brazil's Luciano Pagliarini and Latvian Jan Kirsipuu in the Etampes to Chabris stage on Monday.
Dutchman Erik Dekker now leads the race overall from Germany's Jens Voigt, while Lance Armstrong lies 70th after finishing 44th in the stage.
Britain's Olympic champion Bradley Wiggins withdrew from the race to fly home to be with his pregnant wife.
The stage sparked into life when Frenchman Fabien Sanchez and Spaniard Igor Gonzalez de Galdeano broke away on the 45th kilometre.
The two riders pushed their lead up to seven minutes and 45 seconds before the bunch, led by the Quickstep team of Boonen, caught them with 15km to go.
The peloton looked then poised for a massive sprint until several riders were trapped in a collective fall on a narrow road 7km from the end.
A group of 20 riders, including Boonen and Dekker, opened up a 20-second lead and hung on until the finish line.
The Paris-Nice, which finishes next Sunday, is the first race on the new UCI ProTour programme.
It is also Armstrong's first big event at the head of his new Discovery Channel team.
"It's my first race of the season and I'm not very sharp," commented the 34-year-old Texan.
"I'm probaby slower simply because I stayed longer than usual in the United States.
"When I return to Europe I pay a lot more attention to my form because I train regularly, eat better and have nothing to distract me.
"I've hardly followed the beginning of the season whereas normally I'm on the internet every day following results.
"Now, apart from those of the team, I'm not concerned. Some will see this as a sign of something but in my head everything is okay."
The 20 teams will race another 26 events, including the Tour de France, between now and October.
Italy's Mario Cipollini warmed up for the seven-day Tirreno-Adriatico race by winning the Giro di Lucca on Monday.
Paris-Nice first stage results:
1. Tom Boonen (Bel) 4hr 19min 15sec
2. Luciano Pagliarini (Bra) same time
3. Jaan Kirsipuu (Est) s.t.
4. Jimmy Casper (Fra) s.t.
5. Steven De Jongh (Ned) s.t.
6. Alejandro Valverde (Spa) s.t.
7. Philippe Gilbert (Bel) s.t.
8. Guido Trenti (Ita) s.t.
9. Constantino Zaballa (Spa) s.t.
10. Erik Dekker (Ned) s.t.
Other: 44. Lance Armstrong (US) @ 41sec
Paris-Nice overall standings:
1. Erik Dekker (Ned) 4hr 24min 30sec
2. Jens Voigt (Ger) same time
3. Fabian Cancellara (Swi) at 02sec
4. Vladimir Gusev (Rus) 03
5. Tom Boonen (Bel) 04
6. Kurt-Asle Arvesen (Nor) 07
7. Philippe Gilbert (Bel) 07
8. Thomas Voeckler (Fra) 07
9. Bobby Julich (US) 07
10. Vicente Reynes (Spa) 09
Other: 70. Lance Armstrong (US) 1:08