Cristiano Ronaldo blasted home an 87th-minute winner as Manchester United dug deep into their reserves of strength to move nine points clear at the top of the Barclays Premiership.
Trailing to Brian McBride's first-half opener and outplayed for long periods, it seemed the best Sir Alex Ferguson's men were going to get was a draw after Ryan Giggs had pulled them level.
But Ronaldo had other ideas, picking up possession inside his own half, then embarking on a magnificent run into the Fulham box before driving in his 16th goal of the season with aid of a deflection.
On such victories titles are won and although Chelsea now have a game in hand despite being nine points behind, the celebrations, both after Ronaldo scored and the final whistle had gone, suggested United felt a decisive blow had been struck.
Ferguson has spent the last few weeks stressing if United are to seal the championship, they can expect to encounter some unexpectedly difficult days. This encounter must have been exactly what he meant.
Outflanked before kick-off by Fulham boss Chris Coleman, who played only half the six six-footers Ferguson had been expecting and left Gary Neville out to counter, the United manager then saw his defence given the type of searching examination they have rarely encountered this term.
With McBride and Tomasz Radzinski flying about up front and Michael Brown putting himself about in midfield, the Cottagers got on top in the opening minutes and remained in that position for almost the entire first half hour.
Clearly, the one negative to their dominance was a failure to strike more than once.
Simon Davies flashed a shot wide, Papa Bouba Diop tested Edwin van der Sar and McBride nodded into the side-netting. But the elusive second goal would not come once McBride had put Fulham in front.
The opening goal itself involved some uncharacteristically sloppy defending from United, a measure in itself of how much pressure Fulham had put them under.
Ordinarily, there would have been no danger when Michael Brown lifted a ball over the Red Devils defence for Davies to chase. On this occasion, Van der Sar and Nemanja Vidic got themselves into a muddle, the loose ball broke to McBride and although Rio Ferdinand was well positioned to clear the USA forward's shot as it bounced off the inside of the far post, there was so much spin on it he could only help it over the line.
As has happened so often in the past, the concession of a goal drew United out of their lethargy.
Although Ronaldo was quiet on the right flank, Giggs was devastating on the left.
The Welshman had already found himself in good positions twice without getting a reward. But when Henrik Larsson seized on Moritz Volz's mistake and fed Wayne Rooney, Giggs dropped deep, then met his young team-mate's far-post cross with an volley which flew back into the corner of the goal despite being mishit.
Ronaldo blazed one shot wide and Patrice Evra should have done better after advancing onto the loose ball after Larsson had eased Philippe Christanval out of the way but Fulham survived until the break and then came ever so close to regaining the initiative immediately afterwards.
Radzinski could hardly believe it when he climbed above Wes Brown to meet Michael Brown's cross with a firm header that came crashing back off the bar.
Van der Sar was well beaten on that occasion but he soon made up for any blame lingering over Fulham's goal with a trio of fine stops.
The first two denied Davies, who probably should have done better both times, especially the second when he found himself completely clear after stepping inside Evra.
By the time Van der Sar kept out McBride's low header, Ferguson had introduced another Fulham old boy in Louis Saha.
The Frenchman's arrival, followed by the decision to switch Rooney to the right flank and Ronaldo to the left, saw United finally take command.
And the goal United craved finally arrived three minutes from time when Ronaldo picked the ball up just inside his own half, sped past Clint Dempsey before darting into the box and firing low into the bottom corner.
Fulham thought they should have had a penalty almost immediately when Van der Sar appeared to barge Heidar Helguson over but, to Coleman's disgust, Peter Walton said no and with it went the Cottagers' hopes of claiming a share of the spoils.
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Ronaldo's late winner sealed a win under the most difficult of circumstances for United, playing second fiddle to Fulham for most of the game they managed to get two goals out of nothing thanks to veteran Giggs and not so veteran Ronaldo
