The Arkle Chase winner has not been seen since winning at the Punchestown Festival at the end of April.
But, writing in the Racing Post, trainer revealed he’s leaning towards the Tingle Creek on December 5 at the expense of Hilly Way Chase at Cork 24 hours later.
“Un De Sceaux has come forward really well in the past couple of weeks and we’re looking at starting him off in the Tingle Creek,” Mullins wrote.
“The alternative is the Hilly Way Chase at Cork on the following day, but we’re leaning towards the Tingle Creek for him.”
If Un De Sceaux does turn up at Sandown he could meet Simonsig who delighted trainer Nicky Henderson in a schooling session yesterday.
The 2013 Arkle Trophy hero returned from a mammoth absence of over two and a half years in a hurdle race at Aintree earlier this month and appeared to have lost none of his enthusiasm for the game.
He was eventually unable to reel in resurgent stable companion Bobs Worth, but Henderson could not be happier with his charge ahead of an intended return to chasing in Grade One company.
He said: “Simonsig was very good this morning. He jumped 10 fences and was very good, very quick and very slick. I think we’re still going to the Tingle Creek.”
Sire De Grugy may also turn up at Sandown with Gary Moore confident his stable star is ready to bounce back to form.
Victory in the Grade One contest two years ago ignited a fantastic campaign during which the nine-year-old also landed the Queen Mother Champion Chase at Cheltenham before winning again at Sandown in the Celebration Chase.
He endured a difficult campaign after returning from injury last season and finished last of five on his comeback in the Haldon Gold Cup at Exeter earlier this month, but Moore has been pleased with the progress his charge has made since.
He said: “Sire De Grugy definitely heads to the Tingle Creek. The last three or four days he seems to be showing up like a different horse and looks a bit more like his old self.”