Sale have announced that rugby director Steve Diamond has left the Gallagher Premiership club with immediate effect due to personal reasons.
In a statement released by the Sharks, Diamond said he had taken the decision to "step away from the business".
Paul Deacon will assume first-team responsibility as head coach.
Diamond's shock departure comes just three games into the new Premiership season, and only four days before Sale's Heineken Champions Cup opener against Toulon.
"After 10 proud years with Sale Sharks, I have taken the decision to step away from the business," he said.
"I feel that this is the perfect moment to hand over to someone else, given the club is now stable and in a great position to compete at the highest level.
"We have acquired a world-class training facility, built an academy that is the envy of many Premiership clubs, and constructed a squad that can win tournaments and trophies at domestic and European level.
"I know Simon and Ged (Sale owners Simon Orange and Ged Mason) will continue with the progress we have made together, and I now look forward to taking some time out and planning my next challenge."
The Sharks added: "The club would like to thank Steve for his loyal service and commitment over the years.
"He leaves Sale Sharks in a strong position, having improved the club in many ways, and we wish him every success for the future.
"Paul Deacon will assume responsibility of the first team as head coach while we take stock and plan for the future."
Diamond, 52, took Sale to the verge of a Premiership play-off place last season, but their final game against Worcester was forfeited following a coronavirus in the Sharks camp.
Sale have started the current campaign with two wins and a narrow defeat at Newcastle, and are rated in many quarters as Exeter's main title challengers.