Paula Radcliffe has insisted she was right to defend her ING New York City Marathon title despite picking up a knee injury two weeks before the race.

The 35-year-old world record holder had started the race in search of a third successive New York victory and fourth overall and ran from the front for 23 miles before a tendinitis problem in the back of her left knee that had been bothering her from the 11-mile mark cost her the chance of victory.

Ethiopian rival Derartu Tulu held off Russian Ludmila Petrova to win, with Frenchwoman Christelle Daunay third and Radcliffe bravely finishing fourth.

It was just the third time in 11 marathons that she had not won, dehydration forcing her out of the Athens Olympic marathon in 2004 and the after-effects of a stress fracture of the femur preventing her from challenging for a medal four years later at the Beijing Games.

Yet having not competed in a marathon since her New York victory 12 months ago due to a long rehabilitation from foot surgery that kept her out of the World Championships in Berlin in August, Radcliffe said she had felt compelled to race in New York, particularly as she is not planning to race over 26.2 miles in 2010.

"Maybe I should have like come through a bit steadier this year and just written the year off," Radcliffe said.

"But as I said, maybe I didn't have plans for next year. So I wanted to get this out this year.

"So when this happened so close I had done all the work for the race.

"Had a lot of things gone well this year, I might have let this race go. But it was something that was really important to me just to get out and race after all the work.

"I really thought that it was going to work out. Once I was in the race there was no way I was going to drop out of the race unless it got really so, so sore."

With Tulu and Petrova both older than the Englishwoman at 37 and 41 respectively, Radcliffe promised she still had plenty of time to make a further impact on the women's marathon event with the London 2012 Olympics fewer than 1000 days from now.

"I certainly don't feel that, okay, I had a bad race and I was injured, that that's the end of my career," she said.

"I still think there's a long time to go.

"I've had some bad luck this year, but I don't think it's because I'm older. I think it's because maybe ... once I had that hamstring thing, I had to compensate to things."