The trainer who lured James McDonald to Australia could fittingly hold the key to the young jockey's bid to claim sole ownership of the 2013-2014 the Sydney riders' championship.

McDonald has a share of the premiership lead with Nash Rawiller and he has been booked for four mounts going into Wednesday's Warwick Farm meeting - the last city fixture of the racing season.

"It was a relief to draw level but I'd rather win it outright," McDonald said after Reigning gave him his 70th city winner for the season at Randwick on Saturday.

Because the season's tally includes wins at stand-alone meetings such as Scone and Hawkesbury, conditions for premiership are set by Racing NSW and not the Australian Turf Club.

And the governing body has confirmed the title will be shared if McDonald doesn't ride a winner at Warwick Farm.

Rawiller won the 2012-2013 premiership at the final metropolitan meeting 12 months ago and Darley's John O'Shea could be the trainer to answer McDonald's SOS in a similar manner on Wednesday.

O'Shea was instrumental in enticing McDonald to Sydney in 2012 and the 22-year-old has quickly become one of the country's most sought-after jockeys.

He has booked McDonald to ride Aspen in the Declaration Of War Handicap @ Coolmore Handicap - the last of seven races on Wednesday.

Aspen has raced twice after spell and will back up after making late ground when a close fourth to Niobe at Canterbury last week.

McDonald has also been booked for Moral Compass in the TAB Early Quaddie Maiden Plate, although the last-start bush placegetter has drawn a wide barrier and trainer Stephen Farley has taken the precaution of accepting with the filly at Gosford on Thursday.

The jockey has a dual booking for the Chris Waller-trained stablemates Hero I Am and Bascule in the Testa Rossa @ Vinery Handicap.

Newcastle trainer Kris Lees will complete McDonald's Warwick Farm book with rides on Ay No Digas (TAB Quaddie Handicap) and Flying Jet (theraces.com.au Handicap).

Ay No Digas is an Australian Bloodstock import stepping up to a middle distance in Australia for the first time after winning at Muswellbrook.