The German rider pulled his 17-year-old Olympic champion out of contention after he was found to be “a little lame in trot” when he brought him out to warm up today (27 October).
“I do not really have an explanation, I do not know what happened,” said Michael.
He added he had a “very good feeling” this morning and the horse was going well.
“I was looking forward to it,” he added.
“He had been in his stable for just two hours with my groom. But when he came out, he was stiff.
“I walked him, but he was still wrong and he was sweating. So I decided not to [go ahead].”
Updates on Michael’s Facebook page had shown the horse had been progressing well in the lead-up to Pau.
Michael re-routed Sam to Pau after retiring at the Trout Hatchery at Burghley last month when a miscommunication at the first of the triple brushes at the complex lead to the pair picking up a rare 20 penalties.
World number one
Pau is the last international event in the 2017 calendar and three riders are in contention for the end of year FEI world eventing ranking number one spot.
Michael, whose unbroken streak at the head of the world rankings dates back more than two years to the end of June 2015, currently has 463 points.
Andrew Nicholson and Mark Todd are the only two who could overtake him now — and both have two horses competing in the French CCI4*.
Mark is currently in third equal place ahead of cross-country with NZB Campino. Mark also holds fifth place on Kitubrid Rhapsody, while Andrew is in 11th on Qwanza and 31st with Jet Set.
World champion Michael Jung is to keep the…
There are 111 points available to the winner, dropping in intervals down the leaderboard, so Mark would need good finishes on both horses to be in with a chance of the world number one spot.
Statistics from Equiratings show Andrew needs to finish fifth or higher on either horse to take the title. Strong finishes on both horses could also be enough to take Andrew past Michael.
For a full report from Pau, see next week’s Horse & Hound magazine, on sale 2 November.