Tony Pulis has been sacked as West Brom head coach with the club a point above the Premier League relegation zone and without a win in 10 top-flight games.
The Baggies were beaten 4-0 at home by Chelsea on Saturday.
Albion won their first three games of the season, but have drawn four and lost seven since beating Accrington in the Carabao Cup on 22 August.
Former West Brom manager Gary Megson, who had been Pulis’ assistant, is taking over “until further notice”.
Chairman John Williams added: “These decisions are never taken lightly but always in the interests of the club.
West Brom face Tottenham in the Premier League at Wembley on Saturday and follow that with home games against Newcastle (28 November) and Crystal Palace (2 December).
Pulis is the fifth manager to be dismissed in the Premier League this season. Frank de Boer was sacked by Crystal Palace after only 77 days in charge in September, Craig Shakespeare left Leicester just four months after signing a three-year permanent deal in October, Ronald Koeman was sacked by Everton later that month and West Ham dismissed Slaven Bilic earlier in November.
Only one manager was sacked in the first Premier League season in 1992-93, but there were 15 managerial changes between August 1994 and August 1995, including eight dismissals.
West Brom is now looking to appoint their sixth permanent manager since 2011.