Felix celebrates her victory (Getty Images).

American teenager Allyson Felix won a thrilling 200m final to clinch World Championship gold.

The 19-year-old Olympic silver medallist, who has improved massively this year, came through brilliantly in the final stages of the race to win in 22.16 seconds.

With 50 metres remaining Felix was trailing Christine Arron by a metre but she pulled her back with a devastating change of pace to win by that distance.

Arron had even more problems on her plate when Rachelle Boone-Smith, also from the United States, also kicked past her to pinch the silver medal.