Twenty-four hours after penning a new five-and-a-half-year contract reportedly worth an incredible £85 million ($141 million, 103 million euros), Rooney added to Robin van Persie’s penalty to seal victory at Palace.
United manager David Moyes has been unhappy with some of the decisions that have gone against his side this season, but there were no arguments about the foul on Patrice Evra by Marouane Chamakh that yielded the visitors’ penalty.
Van Persie’s clinical spot-kick eased the pressure on United, after an hour of frustration that had seen the fit-again Marouane Fellaini spurn a glorious chance just before half-time.
Then, six minutes later, Rooney made an instant repayment on his monster deal to bludgeon Evra’s cross beyond Palace goalkeeper Julian Speroni on the half-volley.
Victory left Moyes’s side eight points behind fourth-placed Liverpool, who face Swansea City on Sunday, in the race for Champions League qualification.
Palace remain just two points above the relegation zone, but manager Tony Pulis will know that games such as this are unlikely to decide his side’s fate.
United returned from a warm-weather training camp in Dubai prior to the game and the visitors showed few signs of jetlag in the opening exchanges at a fired-up Selhurst Park.
Adnan Januzaj made a bright start, dragging an early shot off-target, and the 19-year-old would have broken the deadlock in the 17th minute had he not used his left arm to control the ball before firing past Speroni.
Either side of the Belgian starlet’s early contribution, Rooney was on the receiving end of abuse from the home faithful at corners.
As if his bumper contract was not enough, the England ace — who was making his 300th league appearance for United — even had Palace supporters throwing their money at him.
He then came close to putting United ahead, only for Damien Delaney to superbly head his clipped cross off the line before Nemanja Vidic nodded over from three yards.
United goalkeeper David de Gea had little involvement, but the Spanish shot-stopper produced a sharp save to turn Jonathan Parr’s deflected header around his near post.
Moyes saw Fellaini waste a golden chance two minutes before the break when he fired high and wide from 14 yards.
Perhaps one excuse for the Belgian midfielder was his lack of match action, as he was appearing in a United shirt for the first time since facing his former club Everton on December 4 at Old Trafford.
United were patient though, and that was rewarded when Januzaj’s pass found the onrushing Evra, who beat Chamakh to the ball and went down under the forward’s clumsy challenge.
Van Persie stepped up to send Speroni the wrong way before Rooney applied the gloss to a professional display.
Moyes celebrated Rooney’s effort like a man who knew the job had been done and moments later it could have been 3-0 when Van Persie smashed a shot against Speroni’s crossbar.