Sir Alex Ferguson's side looked destined for defeat when a Jonny Evans own goal and strikes from Juan Mata and David Luiz put Chelsea three up by the 50th minute.
But United were handed a route back into the game thanks to two controversial penalties, both converted by Wayne Rooney, before Mexican substitute Hernandez headed the equaliser with six minutes remaining.
The result left Ferguson's second-placed side two points behind Manchester City at the head of the Premier League table, but the manner in which they claimed a point meant they left west London in buoyant mood.
For Chelsea, a draw felt like defeat, a feeling reflected in the boos that greeted the final whistle after they had conceded a three-goal lead for the first time since the inception of the Premier League in 1992.
Andre Villas-Boas's side now sit just one point ahead of fifth-placed Newcastle and face a testing challenge if they are to hold onto a top four place.
The build-up to the game had been dominated by the FA's decision to strip Chelsea skipper John Terry of the England captaincy for a second time, but the way events unravelled quickly diverted attention back to the game.
The FA acted after it became clear Terry will face trial on charges of racially abusing QPR's Anton Ferdinand would be held in July after Euro 2012.
Terry was missing with a knee injury but the fall-out continued with some home supporters booing Rio Ferdinand, Anton's brother, whenever the Manchester United defender touched the ball.
Terry's absence paved the way for Gary Cahill to make his Chelsea debut following his £7 million transfer from Bolton alongside Luiz at the heart of the Blues defence.
And the centre back quickly found himself at the centre of controversy when his last-ditch challenge sent Danny Welbeck tumbling on the edge of the Chelsea penalty area with 11 minutes gone.
Referee Howard Webb waved away claims for a penalty, just as had two minutes earlier when Ashley Young went down under a challenge from Jose Bosingwa.
It was little wonder, then, that Ferguson was showing signs of frustration although for 36 minutes his side looked in control of the game and were creating the better chances.
The balance of the game swung, however, when Sturridge prised open the United defence, easily rounding Patrice Evra before delivering a hard, low cross from close to De Gea's near post.
De Gea stuck out a leg to block the cross but succeeded only in deflecting it against Evans and off his stomach into the goal.
And any hopes United had of quickly getting back on level terms disappeared 30 seconds after the restart when Mata met Torres's right wing cross with an unstoppable volley that flew past De Gea.
The visitors again contributed to their own downfall as Chelsea scored again five minutes later.
Sturridge out-foxed Evra once again, this time drawing a foul from the United full back. From Mata's resulting free-kick, Luiz headed goalwards and his effort deflected off Ferdinand and past De Gea.
United looked dead and buried but Ferguson's side were given a route back into the game in the 58th minute when Sturridge and Evra again clashed -- this time in the Chelsea area -- and Webb decided to award a spot-kick that was clinically converted by Rooney.
The introduction of Paul Scholes added to the sense the visitors could regain control of central midfield.
And United scored again in the 68th minute when Webb decided in their favour after Welbeck tumbled over the out-stretched leg of Branislav Ivanovic.
Welbeck seemed as though he was looking for the foul but that made no difference to Rooney, who converted his second penalty of the game.
The comeback was complete in the 84th minute when Hernandez headed home from Giggs' cross after Cech had parried Rooney's powerful shot.
There was still time for Chelsea to threaten a winner and de Gea made two superb saves to keep out Mata's free-kick and Cahill's drive.
Source: AFP
Source: AFP