Zarkava faces first stamina test

Zarkava bids to defend her unbeaten record and add to her Classic haul in tomorrow's Prix de Diane at Chantilly. The Alain de Royer-Dupré-trained filly won the Prix Marcel Boussac as a juvenile before notching an impressive victory in the French Guineas last month.

She is likely to be long odds-on to add the French Oaks to her CV but connections do have slight reservations as Zarkava attempts 10 furlongs for the first time. "The form of her Guineas win is working out with [fourth-placed] Modern Look winning last weekend and the only question is going to be the distance," said Georges Rimaud, racing manager to her owner, the Aga Khan.

"She has never been over 10 furlongs before but we feel it should not be a big issue, although there are other good fillies in there. There is plenty of stamina on her dam's side, but you never know until you try for the first time. There is always a question mark until you know for sure. She's only had four starts but she has already won two Group Ones. She is a very good filly.

"I couldn't say if she is the best filly the Aga Khan has had, but she is certainly one of a very special bunch."

l Casino Drive, considered the main threat to Big Brown's Triple Crown attempt in today's Belmont Stakes, could miss the race after bruising a hoof. Nobutaka Tada, a spokesman for trainer Kazuo Fujisawa, said: "We have not yet scratched him from the race. We think it might be a small stone bruise and we will watch it closely."