Double Olympic cycling champion Victoria Pendleton came eighth riding Mighty Mambo on her amateur jockey debut, in a flat race at Newbury.
Britain's Pendleton, 34, who retired from cycling after the 2012 Olympics, was competing in the one-mile, five-furlong George Frewer Charity Race.
"I loved it," said Pendleton, who only started training to ride as a jockey in March.
"I'm actually slightly cross with myself in the way I started the race."
Pendleton, who won Olympic gold in the sprint at the 2008 Olympics in Beijing and the Keirin at the 2012 Games in London, is aiming to ride in the Foxhunters Chase at Cheltenham Festival in 2016.
|Analysis - BBC Sport's Joe Wilson|
|There is no doubt her 'journey' into horse racing generates publicity. We can expect to see it all in a documentary. A betting company is, inevitably, involved. But when I spoke to her after the race she was adamant it isn't a 'stunt'.Indeed, there is no hiding place on a horse.|
|The leap into jumping Cheltenham's fences next Spring seems like an enormous one but Pendleton told me she has been making good progress on that already under the guidance of the world-renowned equestrian expert Yogi Breisner.|
After the race, Pendleton told BBC Sport that her main concern was not to look "out of place",
She described the experience as "addictive" and said she would be in a different, more competitive, frame of mind the next time she races.
She added: "Mighty Mambo finished really strongly and had I been closer up sooner, you never know where we might have finished.
"Although I've learnt so much already, today has shown me that there's plenty more hard work ahead."
Having ridden eight-year-old Lawney Hill-trained gelding Mighty Mambo, Pendleton is now expected to undertake her category A amateur licence assessment later this summer. It is not yet confirmed whether she will ride on the flat again this season.