Phillips, the 2006 world champion, had been heavily tipped to be a potential gold medallist in Hong Kong, where the equestrian events are being held, but had to pull out when her horse Toytown picked up an injury.
Toytown, who also got injured before the 2004 Athens Games, will be 17 and almost certainly be too old by 2012 so the Queen's granddaughter has now begun the search to find a suitable mount for the London Olympics and took three horses to compete at the Burgie International Horse Trials at the weekend.
Phillips, riding Secret Legacy, pipped overnight leader Nigel Taylor to win and she almost pulled off a remarkable double when she finished runner-up to overnight leader Ruth Edge’s Nick of Thyme in the one-star competition while riding Tiger Lily IX, a skewbald mare owned by her grandmother.
Phillips said: “Tiger Lily means a lot to me as he has been injured and so much has gone wrong for him, but he’s there now and I’m delighted for him, especially as last time I was here at Burgie I had quite a few fences down in the showjumping.
“When I came out of the ring in the two-star event my first thought was thank God I’ve qualified, but then Nigel got those two fences down, and I know just how he feels, it was very sad for him, but obviously I’m very happy for my horse.
"I'm getting a stable together with some really nice young horses but to single one out now would be too difficult.
"The next Games are more than four years away and anything can happen.
“Hopefully with 2012 in mind one of the horses in my yard might come through, but that is a long way away.”
Edge triumphed in the one-star competition, on the seven-year-old bay gelding Nick of Thyme, edging out Phillips, who is one of three reserves currently hoping to replace her at the Olympics.