Aileen Morrison struggled to a disappointing 43rd place finish in the Olympic women's triathlon at Hyde Park on Saturday.
The Derry woman's hopes ended after she crashed on the first lap of the cycling near Buckingham Palace.
Morrison was aiming for a place in the top 10 after a excellent build-up to the Olympics.
Switzerland's Nicola Spirig took gold after a photo finish with Lisa Norden while Erin Densham came in third.
Morrison was regarded as a medal prospect going into the Games after finishing second in races in Japan and Spain to take her up to seventh in the world rankings.
She clocked a time of 2:08.16 at Hyde Park, which was well behind Spirig and Norden, who both finished in 1:59.48.
Morrison trained at a high altitude training camp in Spain in preparation for the Olympic race.