Both horses are owned by Clive Smith and Nicholls tried to avoid running them on the same day by giving Master Minded his seasonal debut at Aintree last month.
However, that did not go to plan with the dual champion chaser trailing in last of the three runners.
Jacob was appointed second jockey to Nicholls in the summer, and while Noel Fehily, who has recently returned from injury, was in the frame for the mount after partnering him to success in the Amlin 1965 Chase 12 months ago, Nicholls stuck with Jacob.
“I have literally just put the phone down to Clive and I can reveal that Ruby rides Kauto Star at Haydock on Saturday, and Daryl rides Master Minded at Ascot,” Nicholls wrote in his Betfair column.
“Obviously, that is all dependent on the horses pleasing me and all going well in their preparation this week.
“Ruby will ride all my Haydock horses on Friday and Saturday, and Daryl will ride my Ascot runners.
“Clearly, it makes sense for Ruby to partner Kauto Star. But while Noel was in the frame for Master Minded, having won the Ascot race on him last year and next time up at Cheltenham too, Daryl is now our second jockey and he gets the ride.
“Furthermore, Daryl has done a lot of work and schooling on Master Minded at home, too.”
Robbie Hennessy was forced to rule out a crack at the race with Rubi Light after a gallop at the Curragh on Tuesday morning revealed his stable star was not quite firing on all cylinders.
Big-race jockey Andrew Lynch was in the saddle, but he felt the six-year-old would benefit from a little extra time to recover from a viral infection and the John Durkan at Punchestown is his new aim.
“We went to the Curragh this morning and he worked well but Andrew pulled up and said he’s just not quite there yet,” said Hennessy.
“He said every day he is improving, but he’s just not 100% and to go for a Grade One with all the travelling involved you have to be 110%.
“So we’re going to leave him and go to Punchestown for the John Durkan which is in three weeks so gives him plenty of time.
“Andrew said a week later and he’d be bang on, but it’s just one of those things.
“I’d imagine the Durkan would have to be a little bit easier. You won’t get much harder than the Haydock race all season.
“It’s hard enough to take on the best horses in Ireland and Britain when you’re 100% never mind when you’re 95%.”
lHurricane Fly heads a field of just six possibles for the Ladbrokes.com Morgiana Hurdle at Punchestown on Sunday.
Willie Mullins’ star performer has won his last six starts, including Champion Hurdles in England and Ireland.
He bids to take his run to seven in the Grade One over two miles, with his potential rivals including stable companions So Young and Thousand Stars.
Jessica Harrington has left in Oscars Well, who is expected to improve for his reappearance at Down Royal earlier this month.
Charles Byrnes, whose Solwhit has taken on Hurricane Fly several times, will try to overturn the likely red-hot favourite with Pittoni.
The five-year-old has won his last four races but is taking a big step up in class.
Voler La Vedette and Unaccompanied, both winners in the last week, were taken out at the confirmation stage. The only other absentee was Canaly leaving Akatara to complete the field.
lFrankel was named Cartier Horse Of The Year at a glittering awards ceremony of invited guests in London last night.
The three-year-old colt, owned and bred by Khalid Abdullah and trained by Henry Cecil, Frankel also took the honours in the Cartier Three-Year-Old Colt category.
Frankel swept all before him in 2011, taking his unblemished record to nine.
His 2011 season included stunning victories in the Qipco 2000 Guineas, St James’s Palace Stakes, Qipco Sussex Stakes and the Queen Elizabeth II Stakes at Ascot on the inaugural British Champions Day in October.
The Galileo colt will remain in training for 2012, when he is likely to step up in distance to 10 furlongs.