Chelsea remain five points clear at the top of the Barclays Premier League after sharing a 1-1 draw with their nearest rivals Manchester City at Stamford Bridge.
Although Man City were unable to make inroads into Chelsea's lead they responded well to Loic Remy's opening goal, David Silva pegging the Blues back shortly before the interval.
Remy, who was recalled to deputise for the suspended Diego Costa, took centre stage by giving the hosts a 41st-minute lead, before a rare mistake by Chelsea goalkeeper Thibaut Courtois allowed Silva to equalise in the final minute of the first half.
Manuel Pellegrini's team controlled much of the second period, but were unable to find a second breakthrough against a resolute Chelsea defence and had to settle for a draw that extended winless league run to three matches.
City overhauled deficits in late runs to claiming the BPL crown in 2012 and 2014, and a similar effort may now be required, as Mourinho's men remain in the driving seat with 15 matches remaining.
Aside from Costa's absence, Ramires came into the Chelsea midfield as Cesc Fabregas missed out with hamstring injury, while Bacary Sagna was a surprise inclusion at right-back ahead of Pablo Zabaleta for Manchester City.
The visitors started sharply, as Courtois beat away a stinging shot from Jesus Navas inside the first 20 seconds and Fernandinho had a low, angled drive deflected wide.
James Milner was alert to dispossess Chelsea right-back Branislav Ivanovic in the 24th minute and play the ball into Sergio Aguero, but Kurt Zouma forced City's top scorer to shoot from an acute angle and Courtois saved comfortably.
Courtois' opposite number, Joe Hart, made his first save of the match from an Oscar effort after an error by Vincent Kompany let Remy escape down the left flank.
John Terry then joined fellow captain Kompany in seeing an error go unpunished, Aguero pulling a shot wastefully wide after the former England man had missed his kick from a 32nd-minute punt down field.
That was a chance the Argentina striker would regret 10 minutes later, as Eden Hazard brilliantly steered Ivanovic's flighted pass back across goal for Remy to convert.
City's response was immediate, as Courtois fumbled a searching Navas cross, Aguero smashed the loose ball back towards goal and Silva prodded home.
Frank Lampard enjoyed warm applause on his return to Stamford Bridge while warming up with the City substitutes, as his colleagues on the field enjoyed an encouraging start the second half.
Silva and Navas combined on the right flank for Fernandinho to plant a header into the turf - Courtois turning the bouncing ball over.
Milner then looped a headed attempt on to the roof of the net, the impressive Navas again supplying the ammunition, and City's control increased as Chelsea's midweek League Cup exertions began to tell.
Lampard finally made a 76th-minute introduction as City attempted a late assault.
However, with Mourinho increasingly animated on the touchline, Chelsea displayed steely resilience in keeping with their manager's siege mentality, as they closed out what could prove to be a vital point in the title race.
Manchester City manager Manuel Pellegrini: "I think that our team tried to win the game from the first minute until the end.
"I am very proud about that because it is not easy to come here to Stamford Bridge against the leaders of the Premier League with very good players.
"We created, especially in the first half, clear chances to deserve more than the point.
"That's why I am not happy about the point but I am happy with the performance."