South Africa's Oscar Pistorius on Friday gets the last chance to salvage his Paralympic Games, after losing two of his three individual sprint titles in spectacular fashion.
The 25-year-old "Blade Runner", the undisputed star of Paralympic sport after last month becoming the first double-amputee to compete in the Olympics, goes in his specialist event, the T44 400m, shortly before 2000 GMT.
With personal best of 45.39sec and the only athlete in the field under 50sec for the one-lap sprint, Pistorius should qualify with ease and will be favourite for Saturday's final, which brings the curtain down on the athletics programme.
Asked about retaining the title, he said after losing his T44 100m crown on Thursday: "I'm desperate for that. I'm looking forward to the 400m."
Pistorius could only manage fourth in the showpiece straight sprint for single and double below-the-knee amputees at the Olympic Stadium on Thursday, which was won in a new Paralympic record of 10.90sec by Britain's Jonnie Peacock.
US sprinter Richard Browne took silver in 11.03sec and Arnu Fourie of South Africa won bronze in 11.08sec, with Pistorius just out of the medals in 11.17sec.
The defeat came after Pistorius sensationally lost his first 200m race in nine years after Brazil's Alan Oliveira came from behind in the back straight to pip him on the line.
Pistorius then hit out at Oliveira and his rivals, claiming that he was at a disadvantage in terms of stride length as his competitors were "a lot taller".
The row about whether his rivals had illegally flouted rules governing the maximum allowed height of prostheses has rumbled on all week, although the International Paralympic Committee has said there were no violations.
Pistorius gained a measure of revenge over Oliveira on Wednesday, as he anchored South Africa to a world record-breaking victory in the T42-46 4x100m relay for single and double below-the-knee amputees and upper limb amputees.
And he was more magnanimous in defeat to Peacock, hailing him as the new star of Paralympic sprinting.
"I can't imagine how happy he must be to do this in front of his home crowd," he told Britain's Channel 4 television. "Well done, it's a great time for him. He's still young and he's got a great future ahead of him."
At a pre-competition news conference on August 28, Pistorius had rejected suggestions that his exertions at the Olympics might have left him too tired to defend all three of the individual titles he won in Beijing four years ago.
"I have had 22 races this year. The Olympics was obviously very important, as are the Paralympics," he explained.
"In essence, we run internationally from May all the way through to September. I ran my second-fastest time last year in September. It doesn't really matter. I'm in the right shape... I feel in great condition to be able to perform here."