Tony McCoy will ride Denman in the totesport Cheltenham Gold Cup on March 19.
McCoy received the call-up to partner the brilliant chaser as Ruby Walsh, Paul Nicholls' first-choice rider, has remained loyal to stablemate Kauto Star.
The 14-times champion jockey has yet to ride Denman, but will be at the helm for the Aon Chase at Newbury on Saturday week before renewing acquaintance at Cheltenham.
Joint-owner Paul Barber said: "In fairness to Paul Nicholls, we had to lay the ghost.
"I'm sure Ruby would have wanted another four weeks to decide, but we have reached our decision -- McCoy rides."
Denman has only ever been ridden under Nicholls' tutelage by Walsh, Christian Williams and Sam Thomas.
Thomas did the steering when the popular chestnut won the 2008 Gold Cup, defeating the Walsh-ridden Kauto Star by seven lengths, but was also on board when he fell at Aintree last spring.
Barber feels the recruitment of McCoy will bolster the chances of Denman wresting away the Gold Cup from Kauto Star, who last year became the first horse in history to regain the Cheltenham showpiece.
He said: "We know that to be taking on Ruby on Kauto Star, we need to have a jockey who is at least his equal.
"We wouldn't want a situation where we were theoretically giving away several pounds.
"You can't do that if you want to win a Gold Cup."
Zaynar is well on target for his Champion Hurdle preparation at Kelso later this month.
Last season's unbeaten Triumph Hurdle winner, owned by the Men In Our Position syndicate headed by bookmaker Victor Chandler, is reported to be in fine shape ahead of the Morebattle Hurdle at Kelso.
"He is fit and well and is going to go up for the Morebattle Hurdle at Kelso on February 18, a race we are now sponsoring," said Victor Chandler spokesman Neal Wilkins.
"That will be his objective and he won't have the cheekpieces back on until Cheltenham.
"He's just been ticking over. He's a good worker at home and they are pleased with his progress."
Zaynar, who has won both his races so far this campaign, is second-favourite at around 5/1 for the Smurfit Kappa Champion Hurdle at Cheltenham on March 16.
There was a surprise result to the Al Tayer Motors Trophy at Meydan as odds-on favourite Presvis was put firmly in his place by Godolphin's Allybar.
Luca Cumani's Presvis, having his first start since finishing third in the Hong Kong Cup, was slowly away in the hands of Kieren Fallon and was inclined to pull for his head during the early stages.
The writing was on the wall for his supporters a long way from home as Ahmed Ajtebi and Allybar took over from the only other runner Zulu Chief and quickened away in the straight to score decisively.
Presvis made up some ground in the straight and managed to claim second.
Ajtebi said: "That was good. It's great to ride a winner for Godolphin at Meydan and any jockey would be happy to be riding these horses.
"I had a bad fall last week but it isn't a big deal."