Craig Levein has been sacked as Hearts boss and will not return to his director-of-football role.
The 55-year-old will however remain at Tynecastle until the end of the season when his contract ends, working to "develop and improve the structure of the backroom and youth operations".
Hearts' 1-0 defeat at St Johnstone on Wednesday leaves the club 11th in the Premiership, level on eight points with bottom club St Mirren, and with just one league win all season.
Levein returned to the club at board level in May 2014 before being appointed manager for a second time in August 2017 following Ian Cathro's sacking.
A club statement said: "The Board of Directors of Heart of Midlothian Football Club has today taken the decision to relieve Craig Levein of his first-team managerial duties.
"The board would like to thank Craig for all of his efforts as first-team manager.
"Craig has worked tirelessly and selflessly, around the clock, to try to achieve success, despite the many challenges with which he has been faced.
"Craig will not return to his previous director of football role and, that being so, will step down from the board.
"He will, however, see out his contract, which runs until the end of the season, working closely with the executive management team in continuing to develop and improve the structure of the backroom and youth operations within the development.
"We are confident that his knowledge and experience will contribute massively to ensuring that, come the end of the season, he will leave the football department in a healthy and thriving state.
"Effective immediately, Austin MacPhee will be in charge of first-team affairs, on an interim basis, while the board begins the process of recruiting a new manager.
"The new manager, and indeed the interim manager, will report directly to the chief executive."
Who could replace Levein?
Speaking on Sky Sports News, reporter Mark Benstead said: "Austin MacPhee will be hard-pressed to convince Hearts supporters he is the ideal long-term choice.
"In regards to some of the names Hearts fans will talk about for now, John Robertson is a club legend, is doing a good job at Inverness Caledonian Thistle, and could come in to lift the morale.
"Jack Ross worked as U20s coach in 2015 but was relieved of that role by Craig Levein and although things did not go to plan for him at Sunderland, his stock is very high in Scotland - and his style of play would also appeal to a lot of fans."
Confirmed Scottish Premiership games on Sky
Sun Nov 10: Livingston vs Rangers (3pm)
Sun Nov 24: St Johnstone vs Aberdeen (3pm)
Sun Dec 1: Ross County vs Celtic (12pm)
Wed Dec 4: Aberdeen vs Rangers (7.45pm)
Sun Dec 15: Motherwell vs Rangers (12pm)
Thu Dec 26: Hearts vs Hibs (12.30pm)
Sun Dec 29: Celtic vs Rangers (12.30pm)