Stamina question-marks hang over Zawraq ahead of Saturday's Investec Epsom Derby but Pat Smullen believes the colt represents his best chance yet of landing racing's 'blue-riband'.

Ireland’s champion jockey finished third on Casual Conquest in the 2008 Derby and rode the favourite Refuse To Bend in 2003 when the 2,000 Guineas winner failed to fire, finishing out of the money behind Kris Kin.

Zawraq doesn't yet have Group One-winning form like those two horses but is unbeaten in both his career starts to date and continues to impress Smullen and trainer Dermot Weld ahead of Saturday's big race.

The Epsom authorities are predicting a largely dry week leading up to the Derby which, with ground conditions currently described as good, could mean watering will be required, a prospect which doesn’t concern Smullen.

Good job

“I certainly wouldn’t like it to get very quick but in fairness to Epsom they do a very good job in producing ground on the quicker side of good but safe. It is always safe ground there and if that’s the case again, I’ll be happy,” the seven times champion said. “The horse has won his two races on soft, and won them well, but I’ve always felt he’d like it better.”

Zawraq pleased his jockey with a weekend workout over a mile and a quarter and although Smullen stressed the gallop wasn’t overly strenuous, he also took positives from it.

“I was happy with him but it wasn’t like he was going racing pace. He’ll only do that on the day. But he’s giving me confidence he can stay,” he said.

“In my eyes he’s the best chance I’ve had in the Derby. Casual Conquest ran a very good race in a good year and ran as we expected him to. Refuse To Bend started favourite and obviously I thought he had a huge chance but it didn’t happen at all for him and he simply didn’t fire.

“This horse gives the feel he has everything required for Epsom. He has a good mind, he’s well balanced and we all know he has the pace. The question is if he can carry that pace over a mile and a half. If he does I think he has a very big chance,” Smullen added.

With the dual-Guineas winner Gleneagles confirmed on course for Royal Ascot’s St James’s Palace Stakes, Zawraq is rated by bookmakers the best Irish chance of Derby success at a general 5-1 second-favourite behind Golden Horn who has been supplemented into the race at a cost of over €100,000.

Betting lists

Speculation that Aidan O’Brien would supplement the filly Found proved off the mark and she also misses the Oaks with Ascot’s Coronation Stakes over a mile her next intended start.

O’Brien is now set to be triple-handed in the Derby with Hans Holbein, Kilimanjaro and Giovanni Canaletto.

Success Days is as low as 14-1 in some betting lists after the Ken Condon-trained Ballysax and Derrinstown Trial winner was added to the Derby field a day ahead of the five-day confirmation stage.

Success Days has thrived on soft going in Ireland this Spring but Curragh-based Condon said: “Andrew Cooper (Epsom clerk of the course) does a superb job with the ground and it is always a little bit slower on the Friday, so if they get some rain I can’t see there being any sting in it. Saturday looks set to be lovely, a picture-perfect Derby day, and we’ll be there.

“He’s won the best two trials in Ireland and certainly deserves his place in the line-up. People can say he’s been winning in small fields and on bad ground but the ground is always soft in Ireland in the spring. He’s in great order and I’m sure he’ll run a good race.”

A total of 15 colts remain in the Derby ahead of the five-day stage with final declarations on Thursday.

Despite Found’s absence, Aidan O’Brien could be represented by up to four fillies in Friday’s Oaks, the champion trainer indicating Together Forever, Qualify, Wedding Vow and the Cheshire Oaks winner Diamondandrubies could join Coolmore’s Newmarket Guineas heroine Legatissimo in the classic line-up.

Last season's Yorkshire Oaks winner Tapestry remains a Ballydoyle possible for Saturday's Coronation Cup, Epsom's older-horse feature.