Johnson, the closest challenger to McCoy in the championship race, was taken to the Royal Devon and Exeter Hospital after Tuesday's tumble on the ill-fated Philip Hobbs-trained Ilico II.

McCoy said: "It's desperately disappointing for Richard, especially at this time of year with so much to look forward to.

"He is a great rider, a true sportsman and I very much look forward to having him back.

"Jump racing is a very demanding sport and things like this bring us all closer together.

"On behalf of myself and my weighing room colleagues, we wish him a speedy recovery."

Johnson faces up to three months on the sidelines.

He was riding five-year-old Ilico II for Hobbs in the 3663 First For Foodservice Novices' Chase when the gelding fell at the fourth fence.

He escaped head injuries but was taken by ambulance to the hospital following the fall.

Johnson, the boyfriend of the Princess Royal's daughter Zara Phillips, has ridden 81 winners this season.

He was the last jockey to win the Cheltenham Gold Cup, triumphing on Looks Like Trouble in 2000.