Champion jump jockey Tony McCoy has ended his partnership with Martin Pipe to become the number one jockey for Jonjo O'Neill.
McCoy has been champion jockey nine times
McCoy has just won his ninth jockeys' title while Pipe has been champion trainer for 14 of the past 16 years.
Such has been Pipe's dominance in recent years that being his stable jockey has been synonomous with being champion jockey.
McCoy has been Pipe's stable jockey for the past nine years and the decision to leave could mean the end of the Northern Irish jockey's iron grip on the riders' championship.
His split with Pipe is believed to be amicable although the trainer is disappointed by McCoy's decision.
"It's been on the cards for some time but we've had a fantastic time together," Pipe told BBC Radio Bristol.
"We're very sad he's leaving because he is the greatest so he's impossible to replace but we will try to find another champion."
The Somerset trainer said it was too early to say who might take over as his stable jockey but McCoy's leading rival Richard Johnson has been hotly tipped for the role.
McCoy revealed he cannot wait to get started on his new partnership.
"It's going to be a huge change in my life and I'm very much looking forward to it," he told the Daily Telegraph.
"I hope to continue to do a good job and will still be trying hard to be champion jockey."
McCoy is expected to ride many O'Neill-trained horses owned by Irish millionaire JP McManus.
McManus is one of jump racing's most famous owners and is one of the largest shareholders in Manchester United.
Among the horses to have carried his famous green and yellow silks are three-time Champion Hurdle winner Istabraq.
McCoy rode 209 winners in the 2003-2004 season (116 of whom were provided by Pipe) while Pipe's 175 winners brought in £2.4m in prize money.
It was yet another title double for the partnership that has dominated racing in the last decade.
Their biggest win together came with Make A Stand in the 1997 Champion Hurdle.