Five winning chances from a book of seven rides makes Brett Prebble a legitimate favourite for tonight's Happy Valley edition of the Jockey Challenge. Douglas Whyte put his opposition away with a race to spare on Sunday, but the boot could be on the other foot as Prebble's book fairly bristles with winning prospects and - most importantly - the majority have drawn favourable barriers on the tricky 'C' rail placement. Namjong Hunter takes the class drop in the opening event and looks one of the key chances, while Whyte rides debutant Winner for trainer Peter Ng Bik-kuen. Punters were barely able to separate them on last night's 7pm tote call, with Namjong Hunter at $54 and Winner at $55. Prebble has the edge in the Class Five 1,800m event (race two) as Sir Lago has finally found a winnable race, while disappointing Majestic Heart (race three) trialled like a coming winner at the Valley on February 14. Whyte seems to have the odds in his favour on board Valley specialist Super General in the fourth, but Prebble is drawn to get all the favours on Ankh Morpork in the fifth. Good Gains (Prebble) and Warm Embraces (Whyte) look to be two of the main chances in the seventh and that completes Prebble's night, while Whyte goes around on topweight Friendly Gains with 133 pounds in the final event. One of the curiosities of this programme is the grouping 'Others' could claim a couple of races and limit the scoring opportunities of the main protagonists. One such example is Willing Storm (Darren Beadman) in the final event. On last night's prices, Prebble was at $2.70 with Whyte at $4.50 (in from $5.00). Matthew Chadwick and Howard Cheng Yue-tin shared the third line at $8.00.