With Jockey Challenge perennial favourite Douglas Whyte looking a touch vulnerable on what could be an unpredictable day at Sha Tin, look to the in-form Zac Purton for value. Whyte returns from suspension booked for eight of the 10 races, and is a deserved top pick, with rides on likely favourites O'Halo, Go Baby Go and Wah May Star. But with a rain-affected turf track with the rail in the tricky 'C+3' position, plus two races on a sloppy dirt surface, anything could happen and the $2.50 offered last night looked like a shaky bet. Weichong Marwing was second favourite at $4.40 with a strong group of nine rides, including Bear Hero, Iron Hawk and Holy Mac. The next three jockeys in betting, all of them Australians, appear the best options, with Purton the pick of the bunch at $8, with the talented rider coming off a double at Happy Valley. Purton's 'banker' is the Danny Shum Chap-shing-trained Fionn's Treasure, who seems better than Class Three and is drawn perfectly in gate three, and he also rides Costa Del Sol and Giants Serapis. Brett Prebble also has some appeal at $8, with a decent eight rides, which includes talented Giggles Forever. Tim Clark was next on $15 and not without a show. He has a short-priced hope in Sea Diamond, plus a group of outside chances including Sir Eagles, Super Caga and Fatboy Sugar.