Chris Wilder's contract was terminated byBoros after less than a year.
After just two wins in their first 11 matches in the Championship this season,Boro are 22nd in the table and have lost their last two games.
"Middlesbrough Football Club have terminated the contract of manager Chris Wilder with immediate effect," the statement said.
In the interim, Craig Liddle, Mark Tinkler and Lee Cattermole will work withLeo Percovich.
Chris and his staff were thanked by the club for their hard work over the past year.
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Neil Warnock left the club by mutual consent after an indifferent start to the season, but one day later, the club's new manager, Chris Wilder, took charge.
They missed out on a place in the play-offs due to a five-point margin, despite the fact that the 55 year old got them back on track with six wins in his first 10 league games.
The table has a championship title on it.
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Since the beginning of the season, one third of all Championship clubs have changed managers.
Shota Arveladze (Hull), Michael O'Neil (Stoke), Danny Schofield (Huddersfield), Rob Edwards (Watford), Steve Morison (Cardiff), and Shota Arveladze (Hull) have all been let go.