Aidan O'Brien is giving St Mark's Basilica a week to prove his fitness for a potential end-of-season run, with discussions looming over the star's potential retirement to stud at Coolmore.
O'Brien revealed on Tuesday that an ongoing infection, initially picked up in the build-up to the Juddmonte International at York in August, had delayed the three-year-old's return to full training having flared up following victory in the Irish Champion Stakes early this month.
The Leopardstown win was a fifth consecutive Group One for the Siyouni colt - and in addition to his Eclipse and both French Guineas and Derby exploits, marked him down as the best of his generation.
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He remains a general 12-1 shot for next month's Prix de l'Arc de Triomphe, but O'Brien is playing a waiting game.
"He's fine," O'Brien told Sky Sports Racing. "We built him back up into full work after Leopardstown but when we did he was just a little bit sore on the cut that he got on the way to York.
"The cut opened up a little bit so we just had to pull back off him for a little bit. Where it was on the front of his near hind joint and as he flexed it kept opening and closing and we couldn't stitch it or do anything.
"He's back doing gentle canters so we'll see over the next five to seven days how that goes and how much it settles down. We'll just have to wait and see which way it's going to go.
"He can go anywhere really, a mile or a mile-and-a-quarter doesn't seem to matter to him.
"All options, everywhere, are open to him. We just have to get him back perfect and go from there."
With multiple Group One successes to his name and a world-class pedigree, St Mark's Basilica's future looks certain to lie at stud, but connections will have to decide whether that comes after a season racing as a four-year-old.
"That's up to the lads [owners, Ballydoyle], they make all those calls," O'Brien said.
"When the time comes for him to go to stud, he will be one of the most important to do so since Galileo.
"What he has done is exceptional and is the perfect blend of courage, speed, movement, shape and physique. It's all there."
O'Brien happy with Arc hopefuls Snowfall and Love
Two stars almost certain to be on the plane to Paris for the Arc are Snowfall and Love.
Both fillies are on the comeback trail after defeats in the Prix Vermeille at ParisLongchamp (Snowfall) and Blandford Stakes at the Curragh (Love).
On Snowfall, O'Brien said: "We're very happy with her. It was lovely for her to go round the track [at ParisLongchamp] and see how she coped with it.
"The ground was quick but we know she's very comfortable on soft ground and gets a mile-and-a-half well.
"It was more of a trial than a championship race but she came out of it very well.
"She's very versatile and Frankie [Dettori] was very happy with her. Obviously she didn't win but I think her last six furlongs were the quickest of any horse in the race and she was going forward.
"Often in a trial it's better to get beat and things not go right than win and everything go right.
"We were delighted with Love's run. The winning filly was rated 110 and we gave her nine pounds so that was a serious run. On ratings, that wasn't far off her very best and we think she has gone the right way since then.
"We went to the Curragh as a trial for the Arc and were very happy with the run."
O'Brien also confirmed this week that Mother Earth would be rerouted to the Breeders' Cup after intended runner Santa Barbara met with a setback.
Santa Barbara, the Belmont Oaks and the Beverly D Stakes winner, is being monitored "day-by-day", while 1000 Guineas victor Mother Earth could head back to Newmarket for the Sun Chariot en route to the USA.
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On Mother Earth's plans, O'Brien said: "She would have the option of going to Newmarket and/or the nine furlongs race at Keeneland. She could do two or just one.
"She's in good form and came out of Leopardstown very well. She didn't have much of a race and put on all the weight and more very quickly after."