Kenya's David Rudisha has spoken of his shock at beating his own world record in the 800 metres final at the Olympic Games.

Rudisha took gold after storming through the first lap in 49.28 seconds and crossing the line in one minute 40.91 seconds.

The race took exactly one tenth of a second off his previous record as all eight finalists set a season's best, personal best or national record.

Teenager Nijel Amos of Botswana claimed silver in a national record of 1:41.73 ahead of Kenya's Timothy Kitum, with Britain's Andrew Osagie taking 0.71s off his personal best despite finishing eighth.