London - Hull City said on Tuesday they had "parted company" with manager Mike Phelan just as the club slumped to the bottom of the Premier League.
The 54-year-old Phelan was only appointed as Hull boss on a permanent basis in October but Monday's 3-1 loss at West Brom left the club with just 13 points from 20 games and in deep relegation trouble.
"The search for a replacement has begun and an announcement will be made in due course," Hull said on Twitter.
"We would like to thank Mike for his efforts both as assistant manager and head coach over the last two years," said a club statement, which came on the same night that Swansea won at Crystal Palace, leaving Hull bottom.
The Tigers, whose last win came on November 6 against Southampton, sit three points behind 17th-placed Palace, but have a far inferior goal difference and cannot afford to let points drain away as they did under Phelan.
Former Birmingham boss Gary Rowett is the early favourite to replace Phelan, with Alan Pardew, recently sacked by Crystal Palace, and Wales coach Chris Coleman among the other frontrunners.
Former England boss Roy Hodgson, Harry Redknapp and Manchester United legend Ryan Giggs are also potential contenders.
"If we carry on that way, we're going to get punished in every game," Phelan told the Hull website after the latest loss, although there had been little sign he was about to get the push.
"Playing well is irrelevant if you can't do the basics. We have to learn and grow quickly. We can't gift teams the opportunities that we do."
Phelan had stepped in after previous manager Steve Bruce left the club shortly before the start of the season. Bruce had only months earlier led Hull into the top flight.
The Tigers won their first two league matches of the season under Phelan, against last year's champions Leicester and Swansea, but have been unable to build on that strong start.
The new manager will have the benefit of an open transfer window in which to do business, although drawing players to a relegation battle may demand a new face with strong powers of persuasion.
Their next game is in the FA Cup third round on Saturday, coincidentally against a Swansea side who appear rejuvenated for now after a change of boss, having brought in Paul Clement to replace Bob Bradley.