Nottingham Forest have sacked manager Mark Warburton, the Championship club have announced.
Forest are 14th following a 1-0 defeat to Sunderland on Saturday. a fourth game in a row without victory.
A statement read: "Nottingham Forest can confirm that the contracts of Mark Warburton and David Weir have been terminated with immediate effect.
"The club can also confirm that Frank McParland has left the club.
"Academy Manager Gary Brazil has been appointed Caretaker Manager and has assumed his new duties this morning.
"The club would like to thank Mark, David and Frank for all their efforts during their time at The City Ground."
📝 #NFFC can confirm that the contracts of Mark Warburton and David Weir have been terminated with immediate effect.
— Nottingham Forest FC (@NFFC) December 31, 2017
➡️ https://t.co/PsR7FiybxJ pic.twitter.com/TAVk0na3bB
Warburton joined Forest on a two-and-a-half-year contract in March with the former Scotland international Weir as his assistant.
The pair had previously worked together at Brentford and Rangers and secured League One promotion for the Bees in the 2013-14 campaign.
Warburton steered Brentford into the Championship playoffs the following season before being appointed manager of Rangers in June 2015.
He led Rangers into the top flight and the Scottish Cup final -- which they lost on penalties to Hibernian -- before leaving the club in February 2017.
Warburton took over Forest with the team in relegation trouble, and only a 3-0 victory against Ipswich on the final day of the season prevented them dropping down to League One.
They started well this season by winning four of their first five games in all competitions, but Saturday's 1-0 home loss to struggling Sunderland was their fifth defeat in seven games.