Nacho Doce / Reuters

U.S. Postal Service team member Lance Armstrong became the fifth cyclist to win the Tour de France five times last year.

He is one for the ages now, his accomplishments beyond sports, his reach global, his legend assured as long as people push pedals competitively. But Lance Armstrong still is not the greatest. To be that, he must win the Tour de France one more time.

But even in America, a public that thinks that cycling is something kids do to get around town must recognize that Armstrong is one of the most remarkable athletes of this or any other generation. After almost dying of testicular cancer, he has done something that only one other person — Spaniard Miguel Indurain — has ever done. He has won the Tour de France, the Indy 500 and Daytona of cycling, five straight times.

In Europe and in much of the world, he is an enormous star and a household name. But people there, who follow the Tour and other races as intently as Americans follow baseball, basketball, and football, know that he is not indisputably the greatest.

There is a man named Eddie Merckx from Belgium who won four straight Tours, missed one because of injury, then won a fifth. His nickname was “Cannibal” because of the way he ate up his opposition. He didn’t pace himself as racers do today, but ran every race he could and blew away the opposition on the Tour.

The Tour is a highly tactical race, and the winner need not win every stage over the three weeks that it is run. Armstrong this year won but one stage, which was all he needed. But Merckx once won eight stages in a single Tour. Many say he would have won more than the five Tours he did, but he burned himself up by going too hard too often.

European fans are certain that Merckx was the best ever, and they are probably right. Indurain, who had high praise for Armstrong, puts Merckx first, and that’s above himself.

Armstrong is 32 years old. He won his previous tours by margins of six minutes and more. This year, he struggled mightily, beating five-time runner-up Jan Ullrich by little more than a minute. Ullrich and the rest of the field thought the American was vulnerable this year. They were right; he was. But he wasn’t beatable.

That’s the mark of greatness and the stuff of legend, to win when defeat is not just a theory, but a very real possibility. It is why Armstrong is more than just a great cyclist who was better than everyone else, more than just an athlete, but an international cultural icon and one of the very, very few true titans of sport.

But he does not yet stand in a class by himself; he is not yet the Pele of cycling. He knows as well as everyone who mobbed the streets of Paris and cheered his record-tying feat that to be above the debate and to separate himself from everyone who has ever pursued a race that was first contested 100 years ago, he must do it one more time.

It is the same in every sport. To lay claim to the best, you have to beat the records set by the greats who came before. Barry Bonds won’t be the all-time home-run king when he ties Hank Aaron; he has to beat Aaron. It’s no different for Armstrong.

It won’t be easy; even when he was winning by six minutes, it wasn’t easy. Age is an implacable foe, and Ullrich, a great cyclist in his own right, and the rest of the field will gather in France next year feeling that they have both a duty and an opportunity.

The duty is to force Armstrong to the absolute limits to get that sixth straight win, to make him earn it as no one has ever earned a victory before. And the opportunity was out there for all to see this year, a champion who is not as dominating as he was before.

Armstrong said he would take some time off to drink this one in and let his body heal after a race in which he crashed twice, suffered from dehydration, and once had to detour through a field to avoid a third crash.

That, too, may be good news for his rivals; in previous years, he has begun training for next year immediately after his victories. Or it could work the other way. The added rest could rejuvenate him.

He doesn’t know and no one will know. He’s trying to enter unexplored territory, to open a new pioneer in a sport in which many have tried to do the same and failed. He has won five straight. Only one man has done that. But no one has ever won six, consecutive or not.

To be the greatest ever at anything is a privilege granted to a handful of the billions of people who have lived and died on this planet. Armstrong has it within his grasp to join them. The countdown has already begun.