Mickey Arthur has been sacked as Australia head coach and replaced by Darren Lehmann, Cricket Australia has confirmed.
The shock move comes just 16 days before the start of the Investec Ashes series.
CA chief executive James Sutherland said: "The timing is far from ideal but we didn't feel we could sit back and hope matters would change without addressing issues critical to a high-performing team culture.
"It obviously isn't the type of change we want to make three weeks out from the Ashes commencing but we believe a change is needed."
CA also confirmed in its website statement that, as part of the coaching restructure, captain Michael Clarke had "sought to step down as a selector of the team".
Sutherland insisted the decision to replace Arthur with Lehmann had not been taken lightly.
"This has been a difficult decision to make but one that we feel is necessary," he said in the statement.
"We are looking to establish a high-performing Australian cricket team that is consistent over a period of time.
"To achieve that, we need all the parts moving in the right direction. Recent on-field results have been too inconsistent.
"Discipline, consistency of behaviour and accountability for performance are all key ingredients that need to improve. And we see that the head coach is ultimately responsible for that.
"The Cricket Australia board decided yesterday that Mickey Arthur should not continue as head coach of the Australian cricket team. In taking this decision, the board accepted the recommendation to make an immediate change as being in the best interests of the team."
Sutherland added at a press conference in Bristol: "I'd like to acknowledge Mickey Arthur, his commitment and dedication to the task and passion for the Australian cricket team.
"Mickey Arthur is a good man; he's tried his utmost to do a good job and unfortunately, at the end of day, he just hasn't quite done that.
"We decided things weren't improving - we could let things be as they are, continue with the status quo or we could make a change.
"There will be people that think the timing is wrong but we're confident this is a decision in the interests of the Australia cricket team and will see improved performance from the team.
"Darren Lehmann is, to us, the obvious choice to come in and replace Mickey. As a cricketer and a coach he has an outstanding record; he's very highly regarded in cricket and within the Australian team.
"His performances recently as coach of Queensland and the Brisbane Heat have seen him win titles in all three formats of the game.
"We've recognised that by giving him development opportunities as a coach, most recently as assistant coach to the Australia A team here in England.
"His performances over that time have been very impressive and by being here now and ready to come into the role we're confident he will be able to take a running start at this job."