Tiffany Porter fourth in second 100m hurdles semi-final

Great Britain's Tiffany Porter has finished fourth in her 100m hurdles semi-final but still has a chance of reaching the final.

Australia's Sally Pearson won the race with a quickest time this year of 12.39s ahead of Jessica Zelinka of Canada.

Porter still has a chance to qualify as herself and Lolo Jones of the United States currently hold the top two fastest-loser positions.

The 24-year-old must now hope that the third-placed athlete in the final semi-final does not run faster than 12.79s.