Riddell rode Jimmy Choux in seven of his eight starts as a 2yr-old for three wins including the Wakefield Stakes at Trentham on a slow track.
Cellarmaster who finished ahead of Jimmy Choux in three other races, is among his rivals tomorrow with James McDonald the rider.
Opie Bosson, who rode Cellarmaster to finish second in the Manawatu Sires' Stakes at his last start in April, is under suspension.
Jimmy Choux was third that day.
David Walsh, who has won the Wanganui Guineas five times, has the mount on Shah. The Peter McKenzie-trained Shah was a winner in heavy ground at the Grand National meeting.
Riddell considers Man O'Mann could win the Northern Hurdles.
The 9yr-old has won his two starts over hurdles, both at the Grand National meeting, with Riddell the rider.
The Melbourne-based Brett Scott has the mount tomorrow.
Man O'Mann is trained at Hastings by Paul Nelson who has won the Northern Hurdles with Chibuli (2002) and Just Not Cricket (2006 and 2007), all ridden by Riddell.
Scott is at Ellerslie to ride Mali Juraj in the Great Northern Steeplechase.
The John Wheeler-trained Mali Juraj ran third to the Grand National Steeplechase at Sandown at his last start.
Scott and Wheeler teamed to win the Northern Steeples with Real Tonic in 2006.
Wheeler has a likely second string in Petushki, a sound third to Counter Punch and Yourtheman in the Grand National Steeplechase at Riccarton last month.
Counter Punch heads the field for the Great Northern Hurdles tomorrow.
He ran third in the 2007 Northern Hurdles.
He won the National Hurdles that year.
Hypnotize, a last-start winner of the Pakuranga Hunt Cup (4900m) at Ellerslie at his with 70kg has 0.5kg more weight over 1500m further tomorrow.
He carried 68.5kg to win the Northern in 2008 and 65kg to win the race in 2007.
Hunterville won a third successive Northern with 66.5kg in 1985.
Fair King, winner of the race last year with 64.5kg, has 1kg more tomorrow.
Joint Effort will be attempting to emulate the Southland-trained Kidunot last year by winning the Northern Hurdles.
The National Hurdles winner will again be ridden by Matthew Cropp, who turned 19 on Tuesday.
