Timmy Murphy will partner Best Mate when the triple Cheltenham Gold Cup winner makes his seasonal reappearance at Exeter on Friday. The horse's regular rider Jim Culloty has been sidelined for several weeks after breaking his thumb two weeks ago.
It had initially been thought that Tony McCoy, the only jockey other than Culloty to have ridden Best Mate in his 19 career outings, would step in.
But connections have plumped for the in-form Murphy, who replaced McCoy as Martin Pipe's first-choice jockey at the beginning of the season.
"I'm really looking forward to riding him, he's obviously a fabulous horse" said the 30-year-old Irishman.
"His record says it all. It's a privilege just to be asked to ride him.
"Having also ridden Beef Or Salmon recently I will have been on the best two chasers around.
"I went down to Henrietta's on Saturday to sit on him and he was everything I expected him to be."
Murphy has been in a rich vein of form recently, racking up seven winners at the Cheltenham Open meeting over the weekend.
Trainer Henrietta Knight said: "We weighed up the pros and cons, obviously Mr Lewis (owner Jim) has a lot of loyalty to Tony McCoy, who has ridden winners for him in the past, but we decided that Timmy Murphy's style of riding would suit the horse better."
Best Mate will face a maximum of six rivals in the �65,000 race at Exeter, which will be screened live on the BBC.
Chief among them is Sir Rembrandt - runner-up when Best Mate clinched his third Gold Cup last March.
The other horses declared at the five-day stage declaration stage were Hand Inn Hand, Seebald, Upgrade, Frenchman's Creek and One Knight.