Jockey Ryan Moore is not allowed to leave the house as he quarantines for 14 days before riding for trainer Aidan O'Brien on Irish Champions Weekend.
The three-time British champion will be aboard leading contenders including Magical on 12 and 13 September.
"He's in total, total lockdown since Saturday night. It's very strange and very different," said O'Brien.
In Moore's absence, Frankie Dettori is set to ride for O'Brien at Doncaster's St Leger fixture.
The trainer is also likely to book other British-based jockeys at the Leger meeting (9-12 September) with travel restrictions in place because of the coronavirus pandemic.
"I haven't seen him actually - I've spoken to him on the phone," added O'Brien of Moore.
"I see his dinner's going off to him every day, the poor fella."
O'Brien said the best is yet to come from Magical, favourite for the Irish Champion Stakes at Leopardstown on 12 September.
Japan is also likely to line up for the race after finishing the King George at Ascot with sore front feet.
He said Love remains on course for the Prix de l'Arc de Triomphe at ParisLongchamp next month.
And he had an upbeat update on Derby winner Serpentine, who is set to run for the first time since his surprise runaway Epsom triumph in Sunday's Grand Prix de Paris before a possible tilt at the Arc.
"He's a solid horse and I wouldn't be fooled by what everyone thinks about Epsom. He doesn't come back, he's relentless," said O'Brien.