Charlton head coach Les Reed has left the club by mutual consent to be replaced by recently sacked West Ham United manager Alan Pardew.
Pardew (left) will hope for more success at Charlton than Reed
Pardew has signed a three-and-a-half year deal at the Valley and becomes the team's third manager this season.
Reed was originally drafted in to replace Iain Dowie but has failed to turn the club's fortunes around.
He managed just one win at the helm and lost to League Two side Wycombe in the Carling Cup quarter-finals.
We have moved very, very quickly to secure Pardew's services
Saturday's 2-0 defeat at Middlesbrough left Charlton seven points adrift of Premiership safety and in increasing danger of losing their top-flight status for the first time in seven years.
And club chairman Richard Murray explained that Pardew's availability prompted the surprise Christmas Eve swoop, which was announced at 1900 GMT.
"We are very fortunate a manager of Alan Pardew's calibre is available and we have moved very, very quickly to secure his services," Murray said in a statement.
Reed was promoted from his job as assistant manager after Charlton parted company with Dowie 12 games into the Premiership season in the middle of November.
But Reed lasted just 41 days in charge - one of the shortest ever Premiership reigns - even though chief executive Peter Varney said his job was not under threat last week.
Alan Pardew guided West Ham to the FA Cup final
Dowie himself had only been appointed in the close-season to replace the long-serving Alan Curbishley, who has now taken over from Pardew at Upton Park.
Charlton's next match is not until Wednesday night when they entertain Fulham, but the club will hold a press conference at 1330 GMT on Boxing Day.
Pardew was sacked by West Ham two weeks ago, after just over three years in charge, less than a month after Eggert Magnusson's £85m takeover of the club.
In that time, he led them into the Premiership via the play-offs and then took them to the 2006 FA Cup final, where they were seconds away from lifting the trophy against Liverpool.
Pardew was previously in charge at Reading and, while there, led them into the League's second tier in 2001/02.
They reached the play-offs for promotion to the Premiership the following season but failed to go up and early on in the next campaign he moved to Upton Park.