Middlesbrough have sacked manager Aitor Karanka, 43, after three and a half years at the club.
This follows a winless streak in Boro’s last 10 Premier League games and currently sit in the relegation zone, three points from safety with 11 games remaining.
They are also the league’s lowest scorers with just 19 goals and were knocked out of the FA Cup by Man City last weekend.
Assistant head coach Steve Agnew will take control of the first team.
Afterwards, Karanka said: “This club will always hold a special place for me.
“I’d like to thank Middlesbrough for a wonderful opportunity and the players, staff and all the people at the club who I have worked with.”
The former Real Madrid assistant manager took over at the Riverside in November 2013 to become Middlesbrough’s first ever non-British boss.
Boro secured automatic promotion to the Premier League last season.
The club met with Karanka and following discussions, Boro said it was in their “best interests” to make the change.
Already, former Leicester City manager Nigel Pearson is the early favourite to succeed Karanka.
Boro had a solid start to the season including a 1-1 draw at Man City, but their form dipped over the winter and without a win since December 17, they dropped into the relegation zone on March 4 for the first time.
Karanka won just 15% of his games in the Premier League, with four wins, 10 draws and 13 defeats. His win rate in the Championship was 52%.
Goals have been hard to come by, despite the £7m signing of Aston Villa striker Rudy Gestede in January and they have scored just three goals in their last 10 league games.
In addition to scoring the fewest goals in the league this season, they have also attempted the fewest shots on target with just 65.
However, they do have the joint fifth best defence in the league, better than Arsenal and Liverpool, with only 30 goals conceded.
They have also conceded 31 fewer goals than Swansea, who are in 16th place.
Boro spent over £20m in the summer, as they brought in midfielder Marten De Roon for £12m, along with wingers Adama Traore for £7m and Viktor Fischer for £3.8m.
They also signed former Man City striker Alvaro Negredo on a season-long loan from Spanish side Valencia.
It was reported that Karanka walked out of the Riverside last March following a row, but returned.
This season he criticized the club hierarchy over a lack of January signings and also hit out at the fans’ behaviour after a 3-1 defeat to West Ham in January, saying the players deserved more respect.
It has also been reported that he had training ground rows with Stewart Downing and then omitted the former England winger and January signing striker Patrick Bamford, from his matchday squad that lost to City on Sunday.
The Boro boss later said he didn’t pick the pair because he wanted “18 fighters“.