Rooney winner gives United breathing room
Rooney's 21st top-flight goal of the season, which arrived towards the end of the first half, proved enough to see off spirited mid-table opposition.
The result sent Sir Alex Ferguson's side, who have won their last six league games, three points clear of neighbours Manchester City at the top of the Premier League table with eight games remaining.
It was far from vintage United, but with their next four games against teams in the bottom six, it is difficult to see where the Red Devils are going to slip up. Having destroyed struggling Wolverhampton Wanderers 5-0 in their last outing, United were hoping Fulham would prove equally obliging opponents with the league delicately poised.
The London visitors were looking to avoid a ninth straight Old Trafford defeat, while Fulham's failure to score a goal at the venue in seven hours of action also filled United with belief they could use this fixture to improve their goal difference.
"For an hour we played very well and we made some decent opportunities but you have to give credit to Fulham," Ferguson told Sky Sports. "They had more left than we did in the last 15 minutes."
Fulham spent the opening exchanges penned inside their own half. But this was a night for patience as United struggled to impose themselves until Rooney struck three minutes before the interval.
Veteran midfielder Ryan Giggs headed an early chance straight at goalkeeper Mark Schwarzer while Patrice Evra proved an unlikely goal threat in the 32nd minute with an overhead kick which flashed narrowly wide.
Rafael da Silva spurned another chance when he shot straight at Schwarzer following good work by the impressive Antonio Valencia. But the ruthless finishing which was so evident eight days earlier at Molineux was missing as Fulham created just as many chances as United before the interval.
Not for the first time this season, Clint Dempsey was his team's main goal threat. The USA international twice tested David de Gea in the space of a few minutes, his second effort a lovely attempted curler from the edge of the area which had United's Spanish keeper diving at full stretch to claw away.
Moussa Dembele also proved a handful but the Belgian lacked composure to hurt United. Yet just when Fulham thought they had survived the opening half without damage, Rooney pounced from close range after Jonny Evans had teed up the striker from Ashley Young's 42nd-minute cross following a mistake by John Arne Riise.
The sighs of relief could be heard all around the ground. United, who meet City in what could be a winner-take-all game on 30 April, dominated possession after the interval but were unable to add to their tally. Schwarzer was forced into action when Giggs played the ball over the top for Valencia, who seemed likely to score, but his shot was straight at the Australian international.
With 15 minutes remaining, United spurned a glorious chance to double their advantage. Schwarzer, who had an excellent game, twice denied Young before Giggs had a goal-bound effort blocked by Brede Hangeland.
United survived a scare in the 89th minute when Fulham substitute Danny Murphy went crashing inside the penalty area following a Michael Carrick challenge. But referee Michael Oliver waved away Fulham's appeals for a penalty as United hung on for their ninth win in ten league games.