Tiffany Porter has qualified for the semi-finals of the 100 metres hurdles at the London Olympics.
Porter could only manage third in her heat in 12.79 seconds, 0.08secs behind winner Alina Talay of Belarus.
She always looked sure of the top-three finish needed for progression, but appeared to be running close to flat out.
The 24-year-old was an injury doubt coming into the Games after she left the track at last month's Diamond League meeting at Crystal Palace in tears, a back injury having flared up.
United States-born Porter lost her British record to Jessica Ennis in her stunning first event of the heptathlon on Friday. The newly-crowned Olympic champion did not line up in the heats, having stuck with her decision not to compete in the hurdles.
The race was delayed by a clear false start, which saw Mali's Rahamatou Drame disqualified.
Porter insisted she was satisfied with the run, saying: "It was very comfortable. The objective was just to qualify and get through to the next round and I did that. I have been very anxious and nervous but I am fine and very confident for the rest of the competition."
On the back injury, she said: "It's fine, I'm very confident and I will go out there and do my very best."
Sally Pearson, the Australian world champion, was the most impressive qualifier, clocking 12.57s, the fastest first-round time in Olympic history.
But Jamaican Brigitte Foster-Hylton, second in the world rankings, was a major casualty as she clattered the fifth hurdle and trailed home seventh.