Arrest new St Leger favourite after Frankie Dettori opts for late switch from stablemate Gregory

Frankie Dettori will ride Arrest, rather than stablemate and former ante-post favourite Gregory, in Saturday's Betfred St Leger due to the soft ground at Doncaster.

Dettori, a six-time Leger winner, had initially opted to ride Gregory in the final Classic of the season, for which all nine runners stood their ground, but with 21mm of rainfall at the course on Tuesday and a further 0.6mm on Thursday morning, the jockey made the decision to switch.

Kieran Shoemark, who has yet to ride Gregory competitively, will now be on board the Royal Ascot winner.

As a result Arrest now tops the betting for the world's oldest Classic, with Paddy Power making him 3-1 favourite ahead of Continuous at 10-3 with Gregory eased to 4-1, although Coral make the John and Thady Gosden-trained stablemates joint-favourites at 10-3.

Speaking to the Racing Post on Thursday morning, John Gosden said: "Frankie has switched to Arrest because it's soft ground at Doncaster, particularly down the back."

Arrest: Frankie Dettori has partnered the son of Frankel on six occasions and has won three timesCredit: Alan Crowhurst

Shoemark, who partnered Arrest in his final piece of work in Newmarket on Wednesday morning with Dettori on Gregory, said of the change of plan: "It's very exciting, I hope he gives a good account of himself. I was very happy with his last run. Circumstances didn't suit him then and he stayed on and showed credit. I'm not worried about the trip at all, I just hope the ground dries out a little bit more."

Dettori, who is preparing for his final British Classic with retirement approaching later this year, has partnered Arrest six times. The first of his three victories on the son of Frankel came in a Sandown maiden, before the pair landed the Chester Vase in May and Geoffrey Freer at Newbury last month.

Arrest's romp in the Chester Vase came on soft ground and led to him starting favourite for the Derby, although quick ground on that occasion was seen as his undoing.

The legendary rider has also enjoyed big-race success on Gregory in the Group 2 Queen's Vase at Royal Ascot.

Following his final appearance in the St Leger, Dettori will jet off to Sweden after securing the ride on defending Stockholm Cup champion Hard One To Please at Bro Park.

Dettori will join Hollie Doyle, who will ride the Archie Watson-trained Outbox – who has finished runner-up in the race for the last two years – in Sunday's race, which contains just over £111,000 in prize-money.

Dennis Madsen, head of racing at the Swedish Racing Authority, Svensk Galopp, said, "We've been following Frankie closely this season and it's evident he's still very much at the top of his game, so hopefully we can expect fireworks in the Stockholm Cup."

Betfred St Leger (3.35 Doncaster, Saturday)

Paddy Power: 3 Arrest, 10-3 Continuous, 4 Gregory, 5 Desert Hero, 8 Middle Earth, 10 Chesspiece, 12 Tower Of London, 25 Alexandroupolis, 50 Denmark 

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