Just how many world-class sprinters does John Size have? Well, he could have one more enter the top ranks on Sunday and join the four rockets he has running in the Group One Chairman’s Sprint Prize.

Perhaps the best example of Size’s extraordinary depth in the sprint division is that while he will dominate the betting for the Group One with Beat The Clock, Mr Stunning, Ivictory and Amazing Kids, he also has unbeaten three-year-old Hot King Prawn contesting a 1,200m Class Two on the undercard.

Size has a total of eight 1,000m or 1,200m specialists rated 100 or higher and has won six of the seven sprint contests at Group level this season.

The 98-rated Hot King Prawn can join his stablemates in triple figures in the Class Two Audemars Piguet Lady Millenary Handicap (1,200m) but will have to overcome some serious obstacles to do it.

Hot King Prawn has to carry the top weight of 133 pounds against mostly older horses, is first-up for more than three months and tackles a turn and 1,200m for the first time.

Jockey Zac Purton has been aboard for each of Hot King Prawn’s five victories, all of them at short prices and each with a sense of ease that indicated a bright future.

Purton said the weight was the biggest concern, pointing to the recent defeat of youngster Lean Perfection when 1.6 favourite as evidence of the adage “weight can stop trains”.

“It’s not easy, there have been a couple of three-year-olds lately that have got to the top of Class Three and hit a brick wall, so we are mindful of that factor, but you can’t keep them locked in a box forever,” he said.

Zac Purton starts the mind games as Ivictory knocks off Beat The Clock in trial ahead of Chairman’s Sprint Prize

The Australian is less concerned about Hot King Prawn’s lay-off and the added degree of difficulty brought by a turn and step up in trip.

“John likes to give his three-year-olds a bit of time once they get to a mark, so there was nothing wrong with him, it was just a matter of letting him develop,” he said.

Hot King Prawn has trialled three times since December, the last of those on April 17 over 1,200m on the all-weather track.

“He has come back in really good order and improved from one trial to the next,” he said. “And, importantly, I think he handled himself well at 1,200m around a corner.”

Another slight concern is an awkward draw, from where Hot King Prawn will have to show his early dash in a race that contains fellow front-runners California Fortune (Joao Moreira), Shamal (Victor Wong Chun) and E-Super (Jack Wong Ho-nam).

“It’s too early to talk tactics, I need to take a good look at the race, but he has shown he has gate speed and I would expect that he will be handy,” Purton said.

Purton and Joao Moreira’s rivalry continues on Sunday with the top two riders in town both with a strong book of rides.

Title race alive as Zac Purton snares five at Happy Valley

The 35-year-old put on a clinic at Happy Valley on Wednesday with five winners to Moreira’s one, including victory in the final three races on the card.

Seven wins is now all that separates Purton and the three-time defending champion with 22 meetings to go in the season.

Purton has excellent chances in the feature races aboard Time Warp (Audemars Piguet QE II Cup), Beauty Generation (Champions Mile) and Ivictory (Chairman’s Sprint Prize).