Manchester City forward Carlos Tevez earned victory at Craven Cottage to maintain his side's Champions League hopes and give Fulham a European hangover.
The hosts still had their famous victory against Juventus fresh in the mind when they found themselves behind to Roque Santa Cruz's opener, with Tevez then extending the lead before the break in the Barclays Premier League clash.
Fulham are comfortable in mid-table and boss Roy Hodgson illustrated his is Europa League and FA Cup priorities by taking off key players - but Danny Murphy pulled a goal back from the penalty spot and they could have snatched a point.
With Liverpool defeated at Old Trafford, City now move above Rafael Benitez's side and know their destiny is in their own hands - if they win the rest of their games they will be in the top four.
Their victory came despite Joleon Lescott suffering a hamstring injury in the warm-up and Javier Garrido getting drafted in but Mancini's makeshift defence was protected well by Gareth Barry and Patrick Vieira, with the Frenchman making his first start since returning from a three-match ban for violent conduct.
Fulham fans were still buzzing from their victory over Juve and almost had more to sing about after coming close to scoring just before City's opener in the seventh minute.
Damien Duff lofted a cross to the far post where Bobby Zamora headed back and Zoltan Gera touched over Shay Given, only for Kolo Toure to acrobatically clear off the line.
The visitors retained the ball and sprung a counter-attack, with Tevez feeding the ball to Craig Bellamy on the right flank. The Welshman's tame shot flicked the heels of Aaron Hughes, struck the post and bounced over Mark Schwarzer, allowing Santa Cruz to poke home as Dickson Etuhu closed in.
It was his fourth goal of an injury-hit season and his first under Mancini, who was rewarded for fielding an attacking line-up against a team that had only lost once at home since September. Their formation often looked like 4-2-4 when they had the ball.
Tevez had tested Schwarzer twice in the first half, the first with a powerful drive that looked set for the bottom corner and then after Paul Konchesky had carelessly given the ball away in a dangerous area.
He then doubled the lead nine minutes before the break, finishing off a flowing move that started from Pablo Zabaleta at right-back. Tevez nut-megged Murphy then found Bellamy, whose floated return pass from the left flank found his team-mate one on one against centre-back Chris Smalling.
It was a case of Manchester United past versus future, with the Argentina forward cutting inside Old Trafford-bound Smalling before finishing crisply past Schwarzer.
Hodgson clearly had one eye on Wednesday's FA Cup quarter-final replay against Tottenham as he took off Zamora and Gera early in the second half, with Clint Dempsey and Stefano Okaka coming on to try to get the hosts back in the game.
City, however, looked likely to add to their lead. Adam Johnson laid on a chance for Santa Cruz that Schwarzer parried, then Johnson cut inside from the right wing and fired a shot that struck the post.
Bellamy was also found by Johnson unmarked in the penalty area and had time to chest the ball under control - but his finish went wide of Schwarzer's upright.
The game appeared to be drifting towards a routine City victory until Lee Probert, with the help from his assistant, awarded a penalty for Barry handling Chris Baird's cross from the right.
Murphy sent Given the wrong way with the penalty to set up a tense finale, with Okaka missing a straightforward chance to equalise and Probert turning down another spot-kick appeal when Vincent Kompany appeared to handle.