Chelsea looked to be rocking when Fulham sub Elvis Hammond made an immediate impact by setting up Brian McBride to score in the 74th minute at Craven Cottage.
His goal equalised Damien Duff's fortunate opener, which took a wicked deflection off Ian Pearce ten minutes into the second half.
Jose Mourinho brought on Lampard, Joe Cole and Eidur Gudjohnsen to try and win it and Lampard responded with a fizzing 20-yarder that bounced off keeper Edwin van der Sar and into the net with two minutes to go.
With Mark Pembridge in particular snapping into tackles like his life depended on it and Steed Malbranque buzzing around the Chelsea defence like a manic mosquito, it was just the start Fulham boss Chris Coleman had hoped for.
Fulham almost went ahead as early as the first minute when Pembridge had a clear chance from inside the area but saw his shot blocked.
Andy Cole then sent a stooping header only narrowly wide from a Pembridge free-kick and Sylvain Legwinski went close from 20 yards after a neat flowing move.
But Chelsea's class wasn't going to be kept at bay forever, and when Arjen Robben cut inside from the right after 25 minutes it needed a smart parried save from van der Sar to keep his shot out.
Duff was also causing problems, while Alexei Smertin tested van der Sar with another long-range effort.
The Whites then had perhaps their best chance of the first half in the very last minute, when Moritz Volz put Cole through with a superb reverse-pass. But unfortunately the former Manchester United man couldn't quite collect it.
It was Chelsea's turn to go close just after the break, when Glen Johnson's fierce left-foot shot was saved by van der Sar and Duff was ruled offside from the rebound.
Then, at the other end, Cole sent a free-header from a Carlos Bocanegra cross even closer as it scraped the left-hand upright.
But it was Chelsea who finally broke the deadlock after 55 minutes when Duff's 18-yard shot took a cruel deflection off Pearce to beat van der Sar.
Fulham could hardly believe it, especially when the woodwork denied them again a few minutes later when Papa Bouba Diop's header hit the crossbar from a Pembridge free-kick.
But they did level after 73 minutes when Malbranque found substitute Hammond, only on the pitch for a few seconds in place of Cole, and the striker crossed low for McBride to slide home.
Chelsea brought on Lampard, Gudjohnsen and Cole in a bid to win the game in normal time and it worked.
Lampard first set up a great chance for Smertin and then hit the winner when his 20-yard effort bounced off van der Sar and into the net.