COLIN Tizzard’s chances of training this season’s Cheltenham Gold Cup winner have been enhanced even further, as last year’s winner Don Cossack has been forced into a shock retirement.

Don Cossack, the winner of the 2016 Gold Cup, has had to call time on his career after suffering a setback, trainer Gordon Elliott has announced.

Owned by Michael O’Leary’s Gigginstown House Stud, Don Cossack held off Djakadam to win the most prestigious prize in National Hunt racing last March after Tizzard’s Cue Card fell when going well.

Don Cossack subsequently suffered an injury when being prepared for the Punchestown Festival but had been working towards a return to action next month.

However, Elliott reports the 10-year-old to have heat in his leg, with connections opting to retire their star performer.

Elliott told his Betfair blog: ‘’I am very sad to report that Don Cossack has suffered a setback and will now be retired.

“We found that he had a bit of heat in his leg yesterday and we’ve made the decision to call time.”

That news, as well as the announcement that 2015 winner Coneygree will also not run in the showcase, means that Tizzard’s red-hot favourite, King George winner Thistlecrack, is now an odds-on shot with most leading bookmakers.

Tizzard also has the second favourite in Welsh National winner Native River as well as Cue Card and Alary also in the mix, if connections do not decide to go a different route with them during the Festival.