Robbie Hennessy's Rubi Light is a notable absentee from Saturday's JNWine.com Champion Chase at Down Royal after suffering a viral infection.
The talented six-year-old finished third in last season's Ryanair Chase at Cheltenham, and fell on his seasonal reappearance at Gowran when looking likely to beat Sizing Europe.
He was remounted on that occasion for third place, but will have to wait until either the Betfair Chase at Haydock later this month or the John Durkan at Punchestown at the beginning of next month.
A disappointed Hennessy (pictured right) revealed: "He won't be running on Saturday."
He continued: "He didn't work great this morning, so we got the vets to do a few tests on him.
"He's shown to have a viral infection which will knock him back around a week."
Rubi Light has always been held in high regard by the Hennessys whose colours were carried to Champion Hurdle glory at Cheltenham when trained by John Carr.
As a six-year-old, Rubi Light could hold a major future over fences and the trainer confirmed: "It's nothing serious but he's going to have to have an easy five or six days and that is going to rule him out of this weekend.
"It's disappointing as it looked an ideal race for him to start off over three miles, but these things can happen."
Hennessy is setting his sights back at Cheltenham in the long term and the horse may have the Gold Cup on his agenda this season.
After yesterday's setback he could end up meeting two previous Gold Cup winners earlier than expected.
"I've entered him for the Betfair Chase at Haydock so we'll have a look at that, otherwise it will be the John Durkan at Punchestown in early December.
"At this level there is no easy option so we'll wait and see how he is next weekend and fingers crossed he should be OK."
Kauto Star made his first racecourse appearance of the new campaign yesterday at Exeter, as he worked after an exciting day of racing.
The former dual Gold Cup winner was joined by stable companions Big Buck's and Mon Parrain for a racecourse gallop.
The Betfair Chase is his firm target as he looks to win the race for a fourth time and trainer Paul Nicholls said: "Kauto was full of enthusiasm and travelling like a demon and it's good for them, a day out like this. I'm really pleased to see Kauto going nicely and the idea was to try and finish in a line together."
Nicholls commented on the suggestions that this season is one too far for Kauto Star.
"People are saying Kauto should be retired, but they have to remember that when he's retired people won't get the chance to see him.
"He'll be retired one day but he absolutely adores what he's doing -- he loves being in training and loves life."
Nicholls added: "We're not going to abuse him and we won't ask him to do anything he's not capable of.
"He'll have a couple of runs, it will be the same for him and Denman and we'll see what happens."