Mary Keitany of Kenya came to Manhattan last year as a marathon debutant but returns as the favorite for Sunday\'s New York City Marathon through the five boroughs of the Big Apple.Keitany faded at the finish to place third in last year\'s race but has gone on to win the London Marathon and set a half-marathon world record this year to set the stage for a triumphant return to New York.\"I\'m not the same as last year,\" 29-year-old Keitany told Reuters on Thursday. \"I think I\'m believing in myself since I won in London. I know myself better, that I can do it.\"The women\'s race includes six women with times under two hours 24 minutes including Keitany, Boston Marathon champion Caroline Kilel of Kenya, Russians Inga Abitova and Galina Bogomolova, Isabellah Andersson of Sweden and Buzunesh Deba of Ethiopia, setting up the prospects of a fast race on the hilly course.Abitova, 29, finished second in London last year and along with Bogomolova is in a battle to impress selectors of the Russian Olympic team.Fastest in the field in 29-year-old Keitany, who won London in 2hr 19.19mins, the sixth fastest time by a woman marathoner, and set the half-marathon world record this year.\"What I remember from last year was that it was my first marathon,\" said Keitany. \"I think the last mile I was pretty tired. I think now I\'m really more prepared than last year. I believe in myself for Sunday.\"Another intriguing competitor is Briton Jo Pavey, who at age 38 is campaigning for one of three British spots in the marathon for the 2012 Olympics.Pavey, a long-established track performer in distances from 1,500 to 10,000 meters, ran 2:28.24 in her maiden marathon in London. Though she met the Olympic qualifying time, competition is stiff for selection.\"It would be absolutely amazing to run in the London Olympics marathon,\" Pavey told Reuters. \"It would be absolutely lovely to run in the streets of London in a home Olympics.\"I\'ve run the 1,500, the 5,000, and the 10,000 in the Olympics, it would be quite fun to do the marathon.\"Pavey, who finished fourth in the 10,000m at the 2007 world championships in Osaka, said she has been inspired to take up the marathon by the achievements of world record holder Paula Radcliffe, against whom she first competed as a school girl in 1988.\"As a distance runner I think you always want to see what you can do for the marathon. It was a new challenge at this stage of my career,\" said Pavey.\"There\'s so many women running well at this age now.\"Even the winner of the Olympics in Beijing was 38 (Constantina Tomescu of Romania), and Paula has hopes to do really well in the Olympics and she\'s the same age as me. I think the boundaries have been totally changed.\"