English Premiership club Sale announced on Tuesday that rugby director Steve Diamond had left 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 responsibilities as head coach.
Diamond's shock departure comes just three games into the new Premiership season, and only four days before Sale's 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."
Sale thanked Diamond for his "loyal service and commitment".
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 outbreak in the Sharks camp.
Sale have started the current campaign with two wins and a narrow defeat at Newcastle, and are rated by many as Exeter's main title challengers.