Over one of the toughest courses the marathon offers, against one of the strongest fields ever assembled, Paula Radcliffe ran the way she always does: like a metronome.

Plenty of other things looked familiar as she raced through all five New York boroughs, including her bib, No. F111, the number Radcliffe wore when she stunned the running world with her first win in London two years ago.

But it wasn’t until the final 200 yards, when she finally pulled away from Kenya’s Susan Chepkemei and into the clear, that anybody — Radcliffe included — could be sure.

In August, she was sitting on a curb in Athens barely three miles from the finish line of the Olympic marathon in 100- plus-degree heat, holding her head in her hands. She was a prohibitive favorite to win there, too, and you’d have to be British to get a sense of the disappointment many of her countryman felt at that moment, as well as the trepidation with which most greeted Radcliffe’s return.

Some marathoners, like prizefighters, never recover from their first defeat. That made Radcliffe’s decision to run just 11 weeks after Athens, risky enough.

For most of her career, the 30-year-old Radcliffe struggled at distances ranging from 3,000 meters through 10,000 meters, hampered by the lack of a finishing kick. Her breakthrough season in 2001 came when she applied the consistency that enabled her to shadow the elite runners in so many of those races — producing lap after lap at near-top speed — to the marathon. After just two years competing at the new distance, she tore off three of the four fastest women’s times in history. Then came the debacle in Athens.

After her win on Sunday, she said she felt more like herself in this race.

“Nothing like that horrible feeling that I had, nothing like that,” she said.

New York offers the toughest of the big-city challenges, an undulating course over a series of bridges that demands patience, punishes runners and results in winning times a good five minutes slower than its London and Chicago counterparts.

Yet Radcliffe, who always runs from the front, separated herself from the pack in the first mile and never looked back. And she did it knowing that anything less than a victory would likely be considered a failure.

Radcliffe had plenty to gain by showing up in New York — a half-million-dollar appearance fee, plenty of publicity for her upcoming autobiography, “My Story So Far,” perhaps even some leverage in her negotiations with Nike on a contract that expires at the end of this year. But she had even more to lose.

As the debate about when and where to make her comeback raged on the other side of the pond, everybody from past Olympic champions to promoters weighed in. The consensus was that Radcliffe should lay low for a while and make her comeback in small, out-of-the-way, cross-country events. The size of the risk was summed up perfectly by David Bedford, London’s race director, on the eve of Radcliffe’s start in New York.

“If she can draw a line under Athens, it’s a great strategy to come here and race. By drawing a line I mean win it — no more, no less. And if she doesn’t?” he said. “How many times can a prizefighter get knocked out and get back into the ring?”