In sport's battle of the sexes it's nearly always the men that have the upper hand, but horseracing is the exception to this rule.

Tomorrow night, America's unbeaten mare Zenyatta can make it 14 wins from 14 starts by eclipsing Aidan O'Brien's superstar colt Rip Van Winkle in the $5million Breeders' Cup Classic (11.45) at Santa Anita.

Europeans celebrated a record five winners at last year's Breeders' Cup and, observing that the new synthetic Pro-Ride surface on California's premier racecourse favours the raiders, many feel that Rip Van Winkle, who has no superior over a mile on grass, is the banker of the meeting.

However, while this step up to 12 furlongs is not a problem, Rip Van Winkle's well-documented brittle feet have given the Ballydoyle team no end of headaches this week and, following such a preparation, it is a huge gamble switching surfaces.

Furthermore, though O'Brien's three-year-old was awesome at Glorious Goodwood and dug deep to win the QEII at Ascot, the fact is he has been drawn out in the parking lot in stall 10 and jockey Johnny Murtagh, who believes that the colt is happiest when calling the shots out in front, might be stretched to dictate matters from his wide stall.

Zenyatta, trained by Santa Anita-based John Shirreffs, is taking on colts for the first time, but she has brushed aside her own sex with the minimum of fuss and is such a strong finisher in her races that jockey Mike Smith is convinced that she will improve for going up in distance, saying "the faster they go early on, the easier she will win".

Summer Bird, the Belmont winner, is all the talk around the barns in California, but Mine The Bird, the Kentucky Derby winner, clocked a two-second faster time when doing what the Americans call "bullet work" over the track last week, and at 25-1 he is over-priced.

However, Zenyatta's biggest danger could prove to be Henry Cecil's Twice Over.

Cecil has never had a winner at the Breeders' Cup but Twice Over's recent Champion Stakes triumph at Newmarket vindicated the trainer's decision to take in two lesser events as a dress-rehearsal in an attempt to boost the colt's confidence following a tough midsummer battle with the all-conquering Sea The Stars in Sandown's Eclipse.