Prince Harry rushed to help an athlete competing for a place in the Invictus Games after the wind blew over her lightweight racing wheelchair.
RAF medic Anna Pollock had just posed for a picture with the prince when she tipped over on the windy track in Bath.
She joked to the prince: "Are you sure you had nothing to do with it?"
In a speech to injured service men and women hoping to compete in Florida in May, the prince urged them to become ambassadors for the "Invictus spirit".
He addressed UK team hopefuls - including Ms Pollock, 33, from Middlesbrough - competing for one of 100 places across 10 sports at the trials at the University of Bath on Friday.
"It's not necessarily about selection but it's about the whole piece, the way it's fixing you, whether it's mental or physical, to be able to be in this process," he said.
Prince Harry also paid tribute to Henry Worsley, the explorer and former Army officer who died while attempting to cross Antarctica unaided, saying he was the "definition of selfless commitment".
The prince, who launched the Invictus Games for wounded or sick service personnel in 2014, was at the university's Sports Training Village to meet some of the athletes competing in the trials.
He served in Afghanistan twice during a 10-year military career.
This year's Invictus Game will be held from May 8 to 12. The trials are being run by Help for Heroes, supported by the Ministry of Defence and Royal British Legion.