James Doyle admitted it will be tough to choose which of Wathnan Racing duo Shareholder and Aesterius to partner in the Breeders’ Cup Juvenile Turf at Del Mar after putting Karl Burke’s Royal Ascot hero through his paces at Southwell on Thursday.

Shareholder was a length and a half ahead of Aesterius when storming to his Norfolk Stakes success at the Royal meeting, but since then has only been sighted once, when disappointing tried over six furlongs in the Prix Morny.

In the meantime, the Archie Watson-trained Aesterius has gone from strength to strength winning three of his four starts since Ascot and picking up the Group Two Flying Childers Stakes at Doncaster most recently.

Both colts are headed to California next month to contest the five-furlong event won last year by Mick Appleby’s Big Evs, with the owners’ retained rider not pinning his colours to any particular mast at this stage, as both youngsters build towards their big assignment.

Doyle said: “It’s not an easy decision, but a nice one to have to make. I’ll leave it as late as possible before deciding.

“They’re in good shape and they’ve had gallops around a bend and similar workouts – Aesterius went to Kempton and worked anti-clockwise.

“It was not necessarily a test of his ability just a case of giving him that experience of going fast round a turn, similar to Shareholder here today. They are both in good shape and I couldn’t be happier with them.

“They’ve done a good job so far for myself and Wathnan and anything else they do this year will be a bonus.”

Shareholder cost connections €460,000 at the breeze-up sales earlier in the year and having made an immediate impression for the Emir of Qatar’s racing operation, is now on a slight recovery mission when he heads to the country of his sire, Not This Time.

Doyle has partnered the Spigot Lodge-trained youngster in all three outings so far and was happy with what was underneath him during a spin on the Southwell Tapeta.

He added: “I was very pleased with Shareholder, it was a nice exercise for him to do. It was his first gallop around a turn and he handled it well. He’s in good order and I was very pleased.

“He’s very fast, very quick. It is always hard to know how he will get on and it is always a different story when you get out to America. It’s a different test and one he will not have faced before, but you couldn’t be happier with his preparation anyway.”