Didier Drogba powered home a trademark header early in the second half but Branislav Ivanovic's red card gifted the hosts the chance to level in injury time in a dramatic finaleRobin van Persie's last-gasp goal rescued a point for Manchester United as Louis van Gaal and Chelsea boss Jose Mourinho shared a 1-1 draw.
The Portuguese looked to be heading for a famous victory against his one-time mentor at Barcelona after Didier Drogba's second-half strike had given Chelsea the lead.
|By Liam Twomey
Even in a rebuilding season, Manchester United retain the ability to make an afternoon at Old Trafford a tortuous experience. Chelsea return to London with their unbeaten record intact but a bitter taste in their mouths after Robin van Persie snatched a point for the hosts in a finale reminiscent of the Sir Alex Ferguson era.
Louis van Gaal reverted to the classic Fergie playbook, seeking to embroil the Premier League leaders in a battle and assail them down the flanks. Marouane Fellaini produced the best performance of his short and troubled United career to stifle Cesc Fabregas, yet Chelsea still looked like winners when Didier Drogba stole in at the near post to head home the Spaniard's pinpoint corner.
United, however, appear to have recovered the spirit they lost under David Moyes, pressuring Branislav Ivanovic into a rash challenge that led to a second booking and a free-kick that yielded Van Persie's chaotic equaliser.
Much was made before this match about the friendship between Van Gaal and Jose Mourinho, and the truth is that when the dust settles, neither will be too unhappy. United have the biggest result of their brave new dawn, while Chelsea are unbeaten and done with Manchester for the season.
The point means that Chelsea's lead at the Premier League summit is now four points over Southampton, while they are six points better off than Manchester City following the defending champions' 2-1 defeat at West Ham on Saturday.
United, meanwhile, got back to winning ways after their lacklustre 2-2 draw against West Brom on Monday.
Marouane Fellaini was rewarded from his goalscoring appearance in that game with a start in midfield at the expense of Ander Herrera, while Chris Smalling replaced the injured Phil Jones at centre-back.
Diego Costa and Loic Remy missed out for Chelsea due to a virus and a groin problem respectively, meaning Drogba played as their attacking spearhead.
There was a full league debut for Filipe Luis as regular left-back Cesar Azpilicueta began a three-match suspension.
Van Persie led the United attack alone as suspension and injury deprived Van Gaal of Wayne Rooney and Radamel Falcao, and the Dutch striker had his first clear opening in the 23rd minute.
Adnan Januzaj's throughball was threaded through the Chelsea backline but goalkeeper Thibaut Courtois was out quickly to block Van Persie’s effort.
Marcos Rojo and Smalling were fortunate not to be penalised for wrestling John Terry and Ivanovic to the ground in the penalty area from a 36th-minute free-kick and Argentina international Rojo continued a shaky start when his error allowed Drogba to test David de Gea.
Playing against his former club, Juan Mata was afforded plenty of room when Angel Di Maria slid a free-kick towards him in first-half stoppage time, but the Spain playmaker shot woefully off target.
Fellaini fired narrowly wide from the edge of the box under pressure at the start of the second half, but Chelsea found the opening goal in the 53rd minute.
After Eden Hazard had cut in from the left flank and exchanged passes with Drogba to draw a superb save from De Gea, the veteran striker escaped Rafael Da Silva's attentions at the near post to head home the resulting set-piece.
Right-back Ivanovic again made his presence felt in the United area with a storming 69th-minute run but pulled his shot wide from an acute angle.
Courtois denied Van Persie with his legs in the 79th minute but the same player gave the Old Trafford faithful a timely reminder of the late drama of the Alex Ferguson years by levelling the match deep into stoppage time.
Ivanovic earned his red card for bringing down Di Maria, who picked himself up to deliver an excellent free-kick.
Courtois saved well from Fellaini’s header initially, although he was helpless as Van Persie slammed home the rebound to send Van Gaal's men into next weekend's derby against City in high spirits.