Two Australians qualify for BMX semis

Australian riders Sam Willoughby and Khalen Young emerged unscathed amid all the thrills and spills of the London Olympics men's BMX event to qualify for the semi-finals.

Willoughby, the world No.1 ranked rider, finished third in his heat after his five runs at the BMX track at Olympic Park on Thursday, which was good enough to earn him a spot in the next round.

And compatriot Khalen Young overcame a fall in his first run to also progress through to the semis, due to be run on Friday.

Riders had plenty of difficulties in the early stages of Thursday's quarter-finals, with seven out of the first nine runs featuring a fall or crash as competitors negotiated the sharp and steep turns.

Meanwhile, the news was not so good for the third Australian in the field, Brian Kirkham, who crashed in his first run of the day and was unable to make up enough ground to secure a spot in the next round.

Riders will be split into two heats in the semi-final, with the top four from each one after three runs progressing through to the gold medal round.