Paris ? Lance Armstrong’s bid for a record-tying fifth straight win in the Tour de France, a punishing cross-country slog of more than 2,100 miles, begins with a quick dash.

The 4.03-mile sprint through Paris today is only a blip compared to the grind awaiting the 198 riders the next three weeks. But it offers Armstrong a chance to immediately stamp his authority over his rivals.

The prologue, a pedal-as-fast-as-you-can time trial against the clock, starts at the Eiffel Tower and winds its way through tree-lined boulevards, over cobblestones in places, before finishing at the foot of the Champ de Mars, a park in the Eiffel Tower’s shadow. Thousands of fans are expected to line the route.

The winner earns the right to wear the leader’s yellow jersey. With long, hard rides through the French countryside and seven leg-crushing mountain stages ahead, the prologue is not decisive. But it does provide an early gauge.

“The prologue is an important psychological test,” said Armstrong’s coach, Chris Carmichael. “A strong performance … announces a rider’s readiness to contend for overall victory.”

Armstrong’s “goal is to start this year’s race as he finished last year’s, in yellow,” he wrote in a column for The Associated Press.

He won last year’s prologue in Luxembourg, completing a 4.34-mile circuit two seconds faster than France’s Laurent Jalabert, now a cycling commentator.

Armstrong, a 31-year-old Texan and cancer survivor, aims to join Spain’s Miguel Indurain as only the second rider to capture five consecutive Tours. Indurain won in 1991-95.

Three others — Jacques Anquetil, Eddy Merckx and Bernard Hinault — have won five Tours, but none consecutively.

Armstrong starts as the clear favorite in the 23-day race, this time as the Tour celebrates its centennial. But in a race so grueling and unpredictable, Armstrong acknowledges there is little assurance he will be on the winner’s podium July 27 in Paris.

“Lance is the strongest guy,” said Fred Rodriguez, an American who rides for Italy’s Caldirola team. “But you can’t say that’s going to happen until it’s done.”

Jogi Muller, a spokesman for Armstrong’s U.S. Postal Service team, knows how quickly things can go wrong.

“It’s not a free ride to Paris,” Muller said. “It needs one little crash, one little stomach problem or it needs one little bad day and the Tour is lost.”

Armstrong will be tested by Giro d’Italia winner Gilberto Simoni, U.S. rider and former Armstrong teammate Tyler Hamilton and Spain’s Joseba Beloki, last year’s runner-up and third in 2000 and ’01.

“Armstrong has won four Tours in a row and he starts as the big favorite,” Beloki said Friday.

“But his reign will end one day,” he said