The New York City Marathon returns to the streets of the Big Apple on Sunday after a two-year absence, with massive security measures in place after the tragic April bombings at the Boston Marathon.
Last year's 26.2-mile (42 km) run through the city's five boroughs was cancelled in the aftermath of Superstorm Sandy, which devastated areas of New York about a week before the race.
Some 48,000 runners are expected for the renewal of the marathon, which draws hundreds of thousands of people along the race course in a city-wide celebration.
Off the course, scuba divers will check for explosives under city bridges and helicopters will provide overhead surveillance following the tragedy in Boston, where three people were killed and hundreds injured by bombs set off near the finish line.
Elite professional runners will lead the women's and men's fields from the starting line at the Verrazano-Narrows Bridge that connects Staten Island with Brooklyn, before heading into Queens and the Bronx before the finish in Manhattan's Central Park.
Geoffrey Mutai of Kenya, returning to defend his 2011 title, said runners would not let the Boston tragedy affect them.
"What happened in Boston is terrible. As an athlete, we always feel free," Mutai told reporters on Friday. "All security, I'm OK."
Two men and two women will be going head-to-head with a chance to claim a share of the $1 million World Marathon Majors (WMM) jackpot in addition to the $100,000 prize for winning the NYC Marathon.
Tsegaye Kebede, 26, of Ethiopia, the reigning London Marathon winner and world championships bronze medalist, would clinch the $500,000 prize if he wins or finishes second and beats Stephen Kiprotich of Uganda.
The 24-year-old Kiprotich, the world championships winner and 2012 London Olympics gold medalist, would claim the $500,000 bonus if he wins or finishes second and Kebede scores no points.
On the women's side, Priscah Jeptoo, 29, of Kenya must win the race to pocket the half-million bonus. If Edna Kiplagat, 33, finishes first or second and beats compatriot Priscah Jeptoo, she would win the WMM.
Any other scenario would give the prize to Boston and Chicago champion Rita Jeptoo of Kenya, who currently leads the standings and is not competing in New York.
Most runners are trying to set personal bests, raise money for charity or simply meet the challenge of finishing the race.
In other measures taken to ensure safety, 1,400 surveillance cameras have been added to the more than 6,000 video cameras police already watch.
Runners will not be allowed to wear vests with large pockets, masks or any backpacks, and all bags will be checked before the start of the race.
Spectators entering the bleachers have been advised not to bring bags larger than a women's purse, while entry into the park will be restricted for blocks around the finish line.