Chelsea suffered a major setback to their English Premier League title aspirations with a 2-1 home loss against last-place Sunderland.
After holding Manchester City to a draw midweek, Gus Poyet's players were again the party-poopers.
Chelsea could not hold to their lead after Samuel Eto'o opened the scoring in the 12th minute, as Connor Wickham levelled from the rebound six minutes later following Marcos Alonso's long-range effort.
Mourinho's 77-match unbeaten home run as Chelsea boss came to an end in the 82nd minute when Fabio Borini scored from the spot after Cesar Azpilicueta brought down Jozy Altidore in the box.
Chelsea missed the opportunity to dislodge Liverpool from top spot, and the Reds will have the chance to extend their lead to five points at Norwich tomorrow.
Fulham in trouble
Tottenham kept its small hopes of a top-four finish alive with a 3-1 win over Fulham in the Premier League.
Spurs remained sixth in the standings but cut their deficit to fourth-place Arsenal to four points after goals from Paulinho, Harry Kane and Younes Kaboul ended relegation-threatened Fulham's run of two consecutive wins.
Steve Sidwell pounced on an Ezekiel Fryers error to steer in a leveller for Fulham after Paulinho's opener but it was one way traffic after that with Tottenham taking control of the match.
Fulham have now conceded 31 goals from set pieces this season - the most in the Premier League - and their misery was compounded through Sidwell's penalty miss.
Palace keep winning
Mile Jedinak's second-half penalty gave Crystal Palace a 1-0 win at West Ham for a club-record fifth straight win in the Premier League.
Jedinak converted his spot kick in the 59th minute after Pablo Armero had fouled Cameron Jerome in the area to continue Palace's revival under manager Tony Pulis.
The club are now firmly in mid-table, having been in last place when Pulis took over in November.
West Ham are still seven points above the relegation zone, but will have to wait at least another round to make sure of staying up.
Elsewhere, Cardiff drew with Stoke 1-1, Newcastle lost at home to Swansea 2-1 and Aston Villa drew 0-0 with Southampton.