With a full book brimming with quality chances, Brett Prebble is a worthy favourite once again for the Jockey Challenge at Sha Tin this afternoon. The Australian was beaten at odds-on on international day in the Challenge, and again midweek after firming into favourite in in-play betting, but it's hard to go past him as first choice for the day's riding honours again. Prebble was the 2.50 favourite over Douglas Whyte (2.70) last night, with Jeff Lloyd at 7.0 and top apprentice Matthew Chadwick at 10.0. There might be an argument that Chadwick represents some value at those odds, but seven rides against Prebble's full book swings the numbers back to the senior rider. He starts his day with strong claims on the Dennis Yip Chor-hong-trained debutant Bumble Bee, and then the Caspar Fownes-trained Class Fiver East Rider in the second. Later in the card, Prebble looks to have strong chances in Crush On You (race four) and United (race five). He links up with Yip and in-form David Hall several times later in the day on good prospects, and Dane Patrol and interesting debutant Jun Dao are two of his strong mounts. Hall's Jun Dao caught the eye at the barrier trials in winning a heat up the straight last month and, while he has a mountain to climb to beat Brave Kid, he looks the main danger to the favourite.