Garry Monk has been sacked as manager of Swansea City following a run of one win in 11 Premier League games, the Welsh club announced on Wednesday.
Monk, 36, led Swansea to an eighth-place finish last season in his first full campaign at the helm, but he has paid the price for a run of results that has left the club a point above the relegation zone.
"The decision has been made very reluctantly and with a heavy heart," Swansea chairman Huw Jenkins said in a statement on the club website.
"To find ourselves in our current situation from where we were in the first week of September, and considering the drop of performance levels and run of results over the last three months, it has brought us to this unfortunate decision today."
Monk's dismissal was expected, with Jenkins having told journalists "something needs to change" during a trip to London on Tuesday.
Since winning 2-1 at Aston Villa on October 24, Swansea have taken only one point from a possible 15 in the league and were soundly beaten 3-0 at home by leaders Leicester City last Saturday.
A former centre-back, Monk joined Swansea from Barnsley in 2004 and accompanied the club on their rise from the fourth tier, captaining the team that won promotion to the Premier League via the play-offs in 2011.
After injuries curtailed his career, he was appointed interim player-manager following the sacking of Michael Laudrup in February 2014 and kept Swansea in the top flight with one game to spare.
He was rewarded with a three-year contract and oversaw a superb campaign in 2014-15, when Swansea won home and away against both Manchester United and Arsenal en route to their highest league placing since 1982.
They started this season strongly, drawing 2-2 at Chelsea and beating United 2-1 at the Liberty Stadium, but their form has since fallen away drastically.
"It was not a decision we took lightly, especially given Garry's history and standing within the club," Jenkins added.
"And it goes without saying that we wish Garry all the very best for the future and thank him for his tremendous service, not only as a player over the last decade, but also as our manager.
"He will always have a warm welcome at this football club. We hope to appoint a replacement as soon as possible."
Former Swansea and Liverpool manager Brendan Rodgers and David Moyes, recently sacked by Real Sociedad, have been touted as potential successors to Monk.