NEW YORK, Oct 31 - Olympic medalist Deena Kastor is the face of Sunday's New York City Marathon, her image plastered on the sides of buses and in subways promoting the race, which the American predicts will be her toughest.

The women's field for the run through the five boroughs includes Latvian defending champion Jelena Prokopcuka, four-times Boston Marathon and twice Chicago Marathon winner Catherine Ndereba and fellow Kenyan Rita Jeptoo, this year's Boston winner.

"This is by far the most competitive race, even more so than the Olympics, that I've ever been in," Kastor told reporters on Tuesday. "I do expect it to be the toughest challenge of my marathoning career."

Kastor, 33, who claimed the marathon bronze at the Athens Games, is aiming to become the first American woman to win the New York race since Miki Gorman in 1977 and could become a national star with a victory.

Kastor says winning New York has been a goal since she made her marathon debut in the race in 2001. She said she is not concerned with her time - only in victory.

"I don't have any time goals this time around," said Kastor, who satisfied a goal of running under two hours 20 minutes when she won the 2006 London Marathon in 2:19:36, lowering her U.S. women's mark by nearly two minutes.

"I'm not going to be looking at my watch every mile to make sure I'm on pace," said Kastor, who also won last year's Chicago Marathon.

Instead, Kastor said she will keep a keen eye on rivals.

"I'm just going to be checking out the other runners as we cover the territory of the streets. Checking their breathing and foot slapping. You check to see how other people are tiring. The sounds of fatigue, how they are reacting to the pace.

"Just the slightest hint. Whether their head starts tilting to the side a little more to show the strain. As soon as you sense any sign of discomfort is probably a good time to get aggressive."

Kastor says conditioning could help her on the hilly course.

"The New York course is challenging for everybody. The advantage I see is that I am a great hill runner. If I have a chance to win this race, or in the lead pack or with someone else coming into Central Park, I know that I can."

Kastor has stuck to her usual training regimen, running 130 to 135 miles a week at 8,000-foot altitude at home in Mammoth Lakes, California.

"My training has just been incorporating charging hills at the end of long runs, just little specific things to visualize this race a little better. Climbing mountains and envisioning them as bridges, or coming into Central Park."

Kastor said she was raring to go.

"I feel antsy with energy, ready to get out there already," she said."