Zac Purton heads into Wednesday’s Happy Valley showdown with Joao Moreira holding a trump card in the form of Hot King Prawn, but the arch rivals seem otherwise evenly matched as the jockeys’ championship counts down.

Hot King Prawn floats across town for the first time boasting a five from six record at Sha Tin, and the speedy three-year-old has drawn barrier one for his Valley debut in the Class Two Wong Nai Chung Gap Handicap (1,200m).

Last start, Hot King Prawn stepped up to 1,200m for the first time and was defeated but the grey flash should find the smaller track to his liking and drawing the rail seems ideal for the probable leader.

Moreira rides Paul O’Sullivan’s stable stalwart Archippus, a horse who doesn’t win out of turn now his rating is around triple figures but is a threat in this grade over the course and distance.

Sha Tin double gives Zac Purton the championship lead for the first time this season

Not surprisingly, Hot King Prawn’s trainer John Size has stuck with Purton but expect the Australian trainer to throw his full support behind Moreira with key rides down the stretch.

With nine meetings left, Purton has pulled his way back to a one-win lead, 117-116, but the Size-trained cavalry looms.

That’s why Purton needs to make every race count at Happy Valley, where he has enjoyed a clear advantage over the Magic Man this term.

Purton’s overall strike rate of 21 per cent in 2017-18 is only just ahead of Moreira’s 20 per cent, but at the city circuit there is a clear gap between the pair.

The Australian has won 43 races to Moreira’s 31 at Happy Valley, Purton’s strike rate of 20.4 per cent much better than his rival’s 15.4 per cent.

The opening race of the night looks like a fascinating tactical battle between the two leading jockeys as Purton’s Aeroluminance, drawn barrier one, takes on Moreira’s Penzance, drawn two.

The Class Five opener is one of a number of races where the two protagonists are drawn close together and, as we count down to the end of the season, expect the one-on-one tactical battles within the races to increase.

Aeroluminance is one of those horses not good enough for Class Four but doesn’t quite belong in Class Five either and O’Sullivan’s five-year-old should start favourite for the Mount Cameron Handicap (1,800m).

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The gelding’s sole win was over the same distance at Sha Tin when Purton settled midfield from a low gate and it will be interesting whether the jockey wants to use the low draw, especially with Penzance likely to occupy a spot close by, just forward of midfield.

Aeroluminance comes out of the same race as Penzance over this course and distance three weeks ago where they were second and third respectively.

Purton goes without a ride in race two but Moreira links up with David Hall again aboard Heroic Guru in the Class Four Mount Nicholson Handicap (1,650m).

Heroic Guru hasn’t won for more than two years but the seven-year-old showed last start that he won’t be in Class Four for long with an eye-catching second under Moreira over a mile at Sha Tin.

The gelding has been competitive at Happy Valley previously and strikes an average looking contest.

Later in the night, a step up in distance looks ideal for Moreira’s ride Thou Shall Sing in the Class Four Shouson Hill Handicap (1,200m).

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After closing off well late at his first two starts up the straight at Sha Tin, Chris So Wai-yin brought Thou Shall Sing to the Valley’s 1,000m course last start.

The three-year-old was put in the right spot by Vincent Ho Chak-yiu but didn’t handle the turn well at all before finishing off only fairly for fifth.

So’s youngster should be better for the experience but also for a less pressure-filled 1,200m race in which barrier three should allow Moreira to find an ideal spot.