The world record-holder was forced to stop two hours and 14 minutes into the race clearly struggling with the injured thigh that had threatened to prevent her competing.

But she regained her composure and battled on to the finish line, determined to put memories of pulling out of the Athens 2004 marathon behind her and completed the race in 2:32.38.

Team-mate Mara Yamauchi came sixth, equalling the best ever performance by a British athlete in an Olympic women's marathon.

Romanian Constantina Tomescu took the gold in 2:26.44 with Kenyan Catherine Ndereba claiming silver, edging China's Zhou Chunxiu into bronze after a battle down the home straight in the Bird's Nest.
The third British runner Liz Yelling finished in 26th place despite suffering a suspected cracked rib in a tumble.

Radcliffe, whose stress fracture injury disrupted preparations for the race, fought back tears as she told reporters: "Fingers crossed for 2012."

She told BBC One: "I was trying to achieve the impossible I guess. The amount of running I've done coming in wasn't enough.

"Cardiovascularly I felt comfortable but my legs had gone. My calf went first then it went up the entire leg and it felt like I was running on one leg.

"But I didn't do all that work for nothing. It's just really frustrating.

"I was going to the finish line no matter what. I did all the hard work and it feels frustrating because cardiovascularly I don't feel like I've run.

"I tried to to the right things in the race, tried to go after Constantina but my legs weren't there.

"I didn't feel sick or in distress, but there was nothing else I could
do."

The 34-year-old Radcliffe admitted the performance of winner Tomescu, who at 38 produced a fine run, has inspired her to keep going until the London Olympics in four years time.

"It's not the end," she added. "I knew I was pushing it coming in with three-and-a-half weeks of running. You can't take shortcuts in the marathon and I guess I learned that today.

"Fingers crossed for 2012. Look at Constantina – maybe I can do that in 2012 if my body holds up. I know in London I'll have all that support.

"I don't think this is redemption for Athens but it would have been for nothing if I hadn't finished."

Yamauchi said she was pleased with her race. "It was really, really good. I felt really happy with sixth.

"She (Tomescu) was very aggressive and I wasn't surprised how she ran. I thought we would catch her but she just held on. There's no way I could have gone with that pace."