Graham Lee is in intensive care after suffering a neck injury in a fall at Newcastle on Friday evening.
The rider was taken to hospital after being unseated from his mount Ben Macdui as the stalls opened for BetUK. Home Of The Acca-Fenwa Handicap.
A statement from the Injured Jockeys Fund said: “Graham was taken by ambulance to the Royal Victoria Infirmary in Newcastle, where he is in intensive care with a neck injury.
“He will undergo further tests today to assess the extent of the injury.”
Lee has ridden under both codes during his lengthy career, with Amberleigh House propelling him onto the front pages in 2004 after the pair won the Grand National for legendary trainer Ginger McCain.
The rider also enjoyed a successful partnership with staying hurdler Inglis Drever, counting the 2005 World Hurdle at the Cheltenham Festival among their seven victories together, while the Ferdy Murphy-trained pair of Another Promise and Kalahari King were also Grade One scorers.
Lee switched his attentions to the Flat in 2012, also striking Group One gold with Trip To Paris in the 2015 Gold Cup at Royal Ascot and Alpha Delphini in the 2018 Nunthorpe.
He had his best season on the Flat in 2014 when he rode 159 winners, with 47 victories on the board this campaign.