Tallent claimed a bronze medal with a courageous performance in the men's 20km walk.

The 23-year-old crossed the line in a time of one hour, 19 minutes, 42 seconds, just 42 seconds behind Russian gold medallist Valeriy Borchin and 1996 Olympic champion Jefferson Perez from Ecuador.

Australian Luke Adams was sixth, while countryman Chris Erickson was disqualified.

Tallent's family was watching from the stand of Beijing's Bird's Nest stadium, including fiancee Claire Woods, who is preparing to contest the women's 20km walk on Thursday.

One of six children raised on the family potato farm at Newlyn Tallent said if not for his fiancee, he wouldn't have won a medal.

"She has been fantastic," Tallent said of Woods.

"We help each other, always giving each other tips, ideas, supporting each other in training. We start training every day together.

"It just makes us a perfect little couple and without her support I wouldn't be here today."

Tallent said it was not until the final two kilometres of the race he began thinking of a medal.

"When Perez took off with about five kilometres to go, I thought that is where the medals are going to be made, so I went with it," Tallent said.

"And then once those two got away I was always fearful the Italian and Chinese guys would come over the top of me," he said, referring to Hao Wang (fifth) and Ivano Brugnetti (sixth).

Tallent held on to snare bronze on Olympic debut.

"I couldn't be more happy, it's an Olympic medal, it was like `you little beauty' - bronze medal at the Olympics, first time, over the moon," he said.

"There was no pressure on me, I don't think anyone was talking about me winning a medal.

"So to come out here and win a medal on the second day (of the athletics program), I couldn't be more happy."

Tallent became the first athlete to taste victory in the Bird's Nest in a World Race Walking Challenge over 20km in April this year.

He is preparing to contest the men's 50km walk on Friday.