Irish jockey Graham Lee has been diagnosed with an unstable cervical fracture and remains in intensive care following a serious incident at Newcastle on Friday.
The 47-year-old Galway native was unseated from his mount Ben Macdui as the stalls opened and he was taken to Royal Victoria Infirmary in Newcastle.
Lee has damage to his spinal cord and other complications and at this stage his condition has been described as "very serious".
A statement from the Injured Jockeys Fund said: "Jockey Graham Lee's MRI scan has shown that he has suffered an unstable cervical fracture causing damage to the spinal cord, as well as damage to blood vessels in the mid-cervical region.
"He remains in ITU with respiratory support at the Royal Victoria Infirmary Hospital in Newcastle, but it has been possible to reduce his sedation.
"This is a very serious injury and at this early time, it is not possible to predict the extent of long term recovery.
"Graham’s family are very grateful for the many messages of support that they have had."
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.