Britain have no reserve rider, so any further injury would seriously diminish their chances, as would any failure to pass Sunday's first horse inspection which British supporters will now have to watch with bated breath.
Yet the four Britons - Ian Stark, Mary Thomson, Richard Walker and Leng's replacement, Karen Dixon - are a strong quartet. They took the team title comfortably at last year's European Championships, where Stark won the individual from Walker and Dixon. This time, however, they face more formidable opposition from the New Zealand world champions.
El Montanya is the venue for the two days of dressage and Wednesday's cross-country. The site's limited access means that only 30,000 spectators will be admitted on cross-country day. This will make viewing a good deal easier than at Badminton, but serious traffic jams are still probable.
Thrilling rounds are anticipated from Thomson's Badminton winner, King William, Stark's choice of Murphy Himself or Glenburnie, and Walker's Jacana, who are all brilliant across country. New Zealanders can be equally excited at the prospect of watching Blyth Tait (the world champion) on Messiah and Mark Todd (the double Olympic champion) on Welton Greylag.
Any one of these riders could hold the individual lead when the contest moves to the Polo Club in Barcelona (the venue for the other two equestrian disciplines) for the final show-jumping phase on 30 July. It is bound to produce some toe-curling tension, especially if the marks are close for the team and individual medals which will be presented that evening.
German riders are certain to take top place on the podium after the team dressage is completed on 3 August. One of their two young women riders - Nicole Uphoff, 25, the defending Olympic champion, or Isabell Werth, 23, who holds the European title - seems bound to take individual gold on 5 August.
Britain have never won a medal of any colour in dressage, but the new young team (Emile Faurie, Laura Fry, Carl Hester and Carol Parsons) could conceivably take the team bronze.
Selection is the first hurdle for four of five riders in the British show-jumping squad. Only John Whitaker's place is secure. Suspense drags on for David Broome, Tim Grubb, Nick Skelton and Michael Whitaker, who have to wait until 3 August to hear which one of them will be left out.
Grubb, whose home is in New Jersey, must have begun to think that the American system of six obligatory trials would be preferable. He flew to Europe in mid-May and will have ridden Denizen in eight international shows, plus the optional training competition in Barcelona on 1 August, before he knows where he stands.
A close tussle is likely in the team contest on 4 August, with Britain, France, the Netherlands and the United States as the expected protagonists. Germany and Switzerland could also be in the hunt.
France has a trump card in Eric Navet, the world and European champion, who won his last important battle when his four- month ban for alleged drug abuse to his horse was quashed on appeal.
When John Whitaker rides Milton in the individual final on 9 August, the closing day of the Games, he will have two principal rivals: Navet on the ebulliant stallion, Quito de Baussy, and Jos Lansink, of the Netherlands, on Egano.
GREAT BRITAIN: Three-day event: K Dixon (Get Smart), I Stark (Murphy Himself or Glenburnie), M Thomson (King William) and R Walker (Jacana). Dressage: E Faurie (Virtu), L Fry (Quarryman), C Hester (Giorgione) and C Parsons (Vashkar). Show-jumping squad: D Broome (Countryman or Lannegan), T Grubb (Denizen), N Skelton (Dollar Girl or Limited Edition) J Whitaker (Milton or Gammon) and M Whitaker (Monsanta).Reuse content