Middlesbrough boss Gareth Southgate has been sacked - with the club fourth in the table and bidding for promotion.
His dismissal came in the early hours of Wednesday, shortly after Boro had secured a 2-0 home win over Derby.
The 39-year-old was appointed manager in June 2006, but last season he presided over the club's relegation from the Premier League.
Boro chairman Steve Gibson said: "This has been the most difficult decision I've ever had to make in football."
Shortly before being fired Southgate said: "The margins are fine. We are a point off the top but it would have been very different if we had not won against Derby.
"You wonder about the consequences of defeat. You know four home defeats on the bounce would have been difficult for everyone involved with the club to accept."
Former Crystal Palace boss Alan Smith, described by Boro as a "football consultant", has also left the club.
Southgate, who won 57 caps for England, joined Boro as a player from Aston Villa in a £6.5m deal in summer 2001, and made more than 200 appearances for the club, before he succeeded Steve McClaren as the club's manager.
"Gareth has given Boro magnificent service as a skipper and, in very difficult circumstances, as manager," added Gibson.
"I appointed Gareth in a situation that was greatly unfavourable to him. He is a good man and has all the qualities and integrity that we wanted in a manager.
"However, the time is right for change and that change has had to be made. Gareth will always be welcome at our football club. English football needs people of his stature and we feel certain that this experience will serve him well.
"Gareth deserves another opportunity once he has had the chance to rest and refresh himself."
Prior to Tuesday's win, Boro had lost three successive home games, but their victory over Derby left them only one point behind leaders West Brom.