Robin van Persie's equaliser deep into injury time gave Manchester United a point and kept Chelsea within range of their Premier League title rivals after a dramatic Old Trafford finale.

Didier Drogba's header, glanced in off Van Persie early in the second half, looked to have extended Chelsea's lead at the top of the table to six points until a thunderous conclusion in front of the Stretford End.

In scenes reminiscent of days gone by at the Theatre of Dreams, Chelsea's Branislav Ivanovic was shown a second yellow card for a foul on Angel Di Maria as United applied late pressure.

Di Maria's resulting free-kick saw Chelsea goalkeeper Thibaut Courtois save brilliantly from Marouane Fellaini but Van Persie was on hand to thrash home the rebound and spark wild celebrations around Old Trafford.

Blues manager Jose Mourinho turned away in disgust as Van Persie scored, frustrated that the victory his side deserved for controlling long periods had slipped away in a chaotic conclusion.

The Portuguese's side remain four points clear of second-placed Southampton - and, perhaps more significantly, six points ahead of last season's champions Manchester City - but this is a result that will almost have the after-taste of defeat, even though Chelsea's unbeaten run continues.

Without injured top scorer Diego Costa, the old warrior Drogba stepped into the breach and, when United did threaten Chelsea's defence, keeper Courtois was faultless. The Belgian was powerless to prevent Van Persie's leveller.

Despite the late concession, Chelsea looked ominously powerful and carry all the hallmarks of the team to beat this season.

For United manager Louis van Gaal, there will be pleasure in showing the resilience and fighting spirit of old to earn a point - but also the reality that Chelsea showed him how much ground they still have to make up, despite that £150m outlay this summer.

Blues strikerDiego Costa's "little chance" of playing turned out to be no chance as his lingering hamstring strain ruled him out while United, without suspended captain Wayne Rooney, were also missing the injured Radamel Falcao.

The old friends, and on this day foes, Van Gaal and Mourinho were in no mood to hold back and it was only the finishing touches that were missing in an enthralling first half that saw chances for both sides.

Courtois saved superbly from Van Persie after the Dutchman was played through, and home keeper David de Gea also excelled to save with his legs after Oscar's pass found Drogba only 12 yards out.

There was one highly contentious moment when Ivanovic was dragged to the floor by Chris Smalling as they chased Cesc Fabregas's delivery into the box but referee Phil Dowd gave nothing.

Chelsea increased the tempo and power at the start of the second half and it was only another fine save from De Gea that stopped Eden Hazard as he ran clean through and looked certain to score.

There was no let-off, though, as Drogba escaped his marker - who mystifyingly was the diminutive Rafael - and headed in off Van Persie at the near post. The striker's attempted headed clearance was flimsy at best.

Drogba will hope the goal is not taken off him after Van Persie's unwitting intervention as it will otherwise go down as his first Premier League goal for Chelsea since hescored against Stoke in March 2012.

Scenting the chance to kill their hosts off, Willian forced De Gea into an athletic save and Ivanovic's bustling run into the area ended with a shot flashed across the face of goal.

United were looking to Van Persie to create a spark but he found Courtois in his way once more after creating space inside the area.

Then came that Ivanovic red card, the scramble in front of the Stretford End and United had their point courtesy of Van Persie.

Listen to BBC Radio 5 live commentary on the goals.