Aidan O'Brien has warned US Army Ranger will improve for the run on his eagerly-awaited return to action in the Kilfrush Stud Royal Whip Stakes at the Curragh today.

The Chester Vase winner was favourite to provide the Ballydoyle maestro with his sixth victory in the Investec Derby at the start of June and while he ultimately came up just short, he ran an excellent race in defeat behind the Dermot Weld-trained Harzand.

While the latter has since completed the English-Irish Derby double, US Army Ranger has enjoyed a midsummer break.

"US Army Ranger is back after having a good, long break and is just ready to start back," said O'Brien.

"We've been happy with him since Epsom, but he is just ready to start off and he'll improve a lot for the run at the weekend.

"He was supposed to run in the Juddmonte International (at York on Wednesday) and Found go for the Royal Whip but he just wasn't going to be ready in time so we changed plans.

"Found just had a couple of bits of work to do but she still ran well at York (second in Yorkshire Oaks)

"We're probably looking at the Irish Champion Stakes with US Army Ranger, if all goes well."

Jockey Pat Smullen expects the Weld-trained Fascinating Rock to strip fitter for his return to action.

Last season's Champion Stakes hero at Ascot was beaten by Found and Success Days on his first start of the season in the Mooresbridge Stakes, but comprehensively turned the tables on that pair to claim his second Group One victory in the Tattersalls Gold Cup in May.

The five-year-old has not been seen in competitive action since then, however, and Smullen feels he may need the run as he bids to give weight and a beating to US Army Ranger.

He said: "You always look forward to riding a horse like him.

"It's his first run back after a break and he is a horse that tends to take a run.

"You'd like to think whatever he does on Sunday, it should leave him cherry-ripe for the rest of the season.

"We're getting him ready for an autumn campaign and the English Champion Stakes would look the obvious target for him again, but we'll see.

"It looks a tough race on Sunday and he's got to carry the penalty, but we know he's a very good horse."

Weld also runs possible pacemaker The Steward and the hat-trick-seeking Maneen who steps up in grade following a course-and-distance victory in handicap company.

Ken Condon is hoping to see rain for Success Days, who has been off the track since his third-placed finish in the Tattersalls Gold Cup.

"We've been really pleased with him the last 10 days," said the Kildare-based trainer.

"Our handicapper has rated his last two runs as career-bests, which is pleasing given the injury he had, so it looks like he's improved from his Derrinstown win last year.

"I can't help but wonder, either, if he's a bit better left-handed, he certainly has shown signs of that."