Leading jump jockey Richard Johnson has been given a 12-day ban for taking the wrong course at Exeter.
He will miss the busy Christmas period, including the King George VI Chase at Kempton on Boxing Day.
Johnson, 37, would have been likely to ride fourth favourite Menorah in the big race for trainer Philip Hobbs.
A multiple runner-up in the title race, Johnson had been enjoying a fine run of form which included seven winners at November's Cheltenham meeting.
At Exeter, Johnson was on board the Martin Keighley-trained Benbane Head, who was pulled up after jumping the seventh fence and subsequently taking the wrong course.
The race was won by fellow 11-2 chance Adrenalin Flight.
Stewards ruled Johnson had forgotten the water jump, which was omitted on the first circuit. should be jumped second time around and had gone to bypass it.
His ban runs from 19 December to 2 January.