Martin O'Neill has resigned as Aston Villa manager just five days before the start of the Premier League season.
The popular Irishman led the club to three consecutive sixth-place finishes but was believed to be frustrated with the club's owner Randy Lerner over Villa's lack of clout in the transfer market. Reserve team manager Kevin MacDonald takes over on a temporary basis and will prepare the team for the visit of West Ham on Saturday.
O'Neill said: "I have enjoyed my time at Aston Villa immensely. It's obviously a wrench to be leaving such a magnificent club.
"I would like to pay tribute to the Villa players, my coaching staff and the Villa supporters for all the support and encouragement they have given both the club and me personally during my time as manager. I wish them all the best for the future. "I will obviously be assisting the club in the immediate short-term with regard to the handover of my duties."
The 58-year-old joined Villa in 2006 and won acclaim for building a young side based on local talent. However, he was believed to be unhappy at Villa's inability to keep hold of their top players. Former captain Gareth Barry joined Manchester City last summer, while James Milner is also expected to make the move to Eastlands this month. Winger Ashley Young has also been linked with a move away from the club.
The club's chief executive Paul Faulkner said: "The club would like to thank Martin for the great work he has done at Aston Villa over the past four years.
"He has helped to establish the club in the upper echelons of the Premier League, has taken us to Wembley and we have also qualified for European competition for the past three seasons under his management. We wish him the best in the future."