Sire De Grugy, winner of the Queen Mother Champion Chase at Cheltenham in March, has been ruled out of his intended reappearance in the Shloer Chase at the same course on Sunday after he was found to be lame after a routine gallop at the stable of Gary Moore, his trainer, on Wednesday morning.

The setback also casts doubt on whether the eight-year-old will be ready in time to face Sprinter Sacre, the 2013 Champion Chase winner, when Nicky Henderson’s brilliant two-miler returns from nearly a year on the sidelines in the Grade One Tingle Creek Chase at Sandown on 6 December.

Sire De Grugy appeared to come through his exercise without incident but his lameness came to light shortly afterwards and was of sufficient concern for Moore to rule him out of this weekend’s Open meeting at Cheltenham immediately.

“He’s not going to run on Sunday, unfortunately,” Moore said. “He worked well this morning and was fine straight after but he’s lame now. I’m hoping he’ll be OK for Sandown but it’s up in the air. There’s nothing obvious but he is lame [and] it is a big worry.”

Sire De Grugy gave Moore his first Grade One winner when he took last season’s Tingle Creek, a race which Sprinter Sacre missed after returning an unsatisfactory scope a few days beforehand. Sire De Grugy went on to win the Desert Orchid Chase at Kempton on 27 December, in which Sprinter Sacre suffered his first defeat over fences when he pulled up before the eighth fence. He was found to be suffering from an irregular heartbeat, a problem which Henderson believes has now been resolved.

Sire De Grugy would have been the certain favourite for the Shloer Chase had he lined up but in his absence Nicky Richards’ Simply Ned, the runner-up behind Balder Succes in the Grade One Maghull Novice Chase at Aintree in April, is the new market leader with Paddy Power on 9-4.

Dodging Bullets, from the champion trainer Paul Nicholls’ stable, is next in the list on 5-2, with Alan King’s Uxizandre, who will run in the Shloer in preference to the Paddy Power Handicap Chase the previous afternoon, and Module (Tom George) on offer at 7-2 and 9-2 respectively.

Sprinter Sacre remains favourite for the 2015 Queen Mother Champion Chase at a general price of 5-2, while Sire De Grugy is a best-priced 4-1 to retain the two-mile championship.

Sizing Europe, who won the Champion Chase in 2011 and finished fourth behind Sire De Grugy eight months ago, faces a duel of his own at Clonmel on Thursday afternoon when he lines up against Champagne Fever, the narrow runner-up when favourite for last year’s Arkle Trophy at the Festival meeting.

Sizing Europe will be 13 on 1 January but retained enough of his best form to win a Grade One event at Punchestown in April and, though the race conditions force him to concede 11lb to a rival five years his junior, he could still prove a significant opponent for Champagne Fever as Willie Mullins’ runner makes his first start outside novice company.

Champagne Fever will be ridden by Paul Townend while Ruby Walsh, his regular partner, serves a one-day ban, and Johnny Burke, the new retained rider of Alan Potts, the owner of Sizing Europe, will be aboard Henry de Bromhead’s chaser for the second time after their victory in a Grade Two race at Gowran Park last month.

“On the ratings, we might have a few pounds in hand, but I imagine our fellow might need the run,” Willie Mullins, the trainer of Champagne Fever, said on Wednesday. “If we get the tactics right with him, hopefully he will improve into the horse we thought he was and showed [when winning the Supreme Novice Hurdle] at Cheltenham two years ago.”

Mullins also confirmed on Wednesday that his mare Annie Power, one of last season’s best hurdlers, will remain over the smaller obstacles for the 2014-15 campaign. A Festival target has yet to be decided for the six-year-old, who was beaten for the first time in 11 National Hunt starts when second to More Of That in the Ladbrokes World Hurdle in March.

Barry Geraghty, who rode Jezki to win last season’s Champion Hurdle, will miss the ride on Jessica Harrington’s six-year-old when he makes his seasonal reappearance at Punchestown on Sunday in order to partner Vaniteux, the favourite, in the Greatwood Hurdle at Cheltenham the same afternoon. Mark Walsh is expected to come in for the ride on Jezki in the Grade One Morgiana Hurdle, in which the dual Champion Hurdle winner Hurricane Fly is also a likely runner.

“Nicky [Henderson, who retains Geraghty as his stable jockey] has confirmed Vaniteux will run at Cheltenham and I’ll look forward to riding him,” Geraghty said.

“It’s a great complaint to have two horses like that to potentially ride, but I can’t be in two places at once.”

Ptit Zig, who finished sixth behind Jezki in the Champion Hurdle, made an impressive chasing debut at Exeter on Wednesday afternoon and was immediately installed as one of the early favourites for the Arkle Trophy in March. Paul Nicholls’s five-year-old was a 2-9 chance to beat three opponents and eased to a 10-length success in the hands of Sam Twiston-Davies, the trainer’s new stable jockey.

Prize money for the Group One Lockinge Stakes over a mile at Newbury next May will rise by 64% to £350,000 after the course signed a new five-year sponsorship deal with Al Shaqab Racing, the main ownership vehicle of Sheikh Joaan al-Thani of Qatar. Al Shaqab took the 2014 renewal of the Lockinge with Olympic Glory, and will sponsor the entire seven-race card.