Premier League - Chelsea snatch win over United
After Wayne Rooney fired United into a first-half lead, David Luiz volleyed in an equaliser before Martin Atkinson ruled that Chris Smalling fouled substitute Yuri Zhirkov inside the box. Lampard rifled the 80th-minute spot-kick past Edwin van der Sar to take his team into the top four and inflict United's second defeat of the league campaign.
United, who complained Luiz should have been sent off for a foul on Rooney, saw skipper Nemanja Vidic dismissed in injury time for his second yellow card, meaning the Serbian will miss Sunday's trip to Liverpool.
Chelsea made a bright start and Fernando Torres shot into the net in only the second minute but Atkinson had long since blown his whistle for a foul by Luiz inside the box.
Nani saw a shot strike John Terry on the arm inside the area, although a penalty would have been harsh, but most of the chances were coming at the other end with Florent Malouda testing Van der Sar and Michael Essien seeing a shot deflected wide.
Gradually, United took a grip on proceedings and Patrice Evra could not pick out Rooney in the middle following nice play by Javier Hernandez. Although Nicolas Anelka shot wide on a break, the Blues were fortunate when Rooney got a header all wrong inside the box after an inviting centre by Nani.
Luiz had to make an important interception from a Darren Fletcher cross after Terry gave away possession cheaply and more dangerous centres were fizzed in by Hernandez and Evra as the Red Devils built up a head of steam.
It culminated in Nani feeding Rooney outside the area and the England striker drilled a firm finish past Petr Cech's right-hand and inside the post to open the scoring - ironically in a game he could have missed after the incident with James McCarthy at Wigan on Saturday.
Chelsea produced a response and started to dominate possession before spurning a real opportunity five minutes before the break. Evra fouled Torres, allowing Lampard to fire in a shot from a free-kick. Van der Sar dived to save but the rebound looked to provide Branislav Ivanovic with a simple finish. However, it bounced off the defender at an awkward height and Van der Sar got another touch from on the ground with Vidic blocking on the line.
Carlo Ancelotti's side started the second period with increased impetus and United wasted a couple of decent chances for breakaways with sloppy passes, most notably when Rooney overhit a return to Hernandez.
After Van der Sar fielded a Lampard free-kick, the Blues made a breakthrough on 54 minutes when Essien returned the ball into the box following a corner. Ivanovic got a touch on and Luiz calmly waited before despatching a flashing volley into the net despite Evra's close attention.
Ancelotti threw on Didier Drogba for Anelka and both sides continued to attack with £50million man Torres bending a shot off target after a nervous headed clearance by Smalling.
Rooney had a goal rightly ruled out for offside before deciding to go it alone from an improbable angle following a fine exchange of passes with Nani and sending his shot well wide.
Ryan Giggs came on to equal Sir Bobby Charlton's league appearance record but it was another sub, Zhirkov, who ended up having a major impact.
Drogba smashed a couple of shots off target but Sir Alex Ferguson was fuming when Luiz escaped a second yellow card for a clumsy challenge on Rooney.
With 12 minutes remaining, Chelsea broke quickly and Zhirkov went sprawling after running past Smalling inside the area with referee Atkinson pointing to the spot. It looked a tight decision but there was little protest from the defender and Lampard kept his cool to hit the penalty high into the net past Van der Sar.
Although substitute Fabio da Silva crept into the box to prod a shot against the face of the grounded Cech, much of the late drama came at the other end with Zhirkov only denied when a powerful drive deflected off Vidic and clipped the outside of a post.
Drogba tried to run down the clock and a bad foul by Giggs earned the veteran a yellow card but worse was to follow for the Red Devils when Ramires was hauled down on the edge of the box and Vidic received a second yellow card.
United will wonder how they ended up with nothing and losing their captain for another tough examination at Anfield at the weekend but Chelsea have cut the gap on the leaders to 12 points with a game in hand and a trip to Old Trafford still to come.