Liverpool had chances to make the breakthrough throughout the north-west derby but United goalkeeper David De Gea denied Emre Can, Roberto Firmino and Adam Lallana.
Rooney, who hadn’t scored at Anfield since 2005, broke the deadlock in the 78th-minute with a close-range finish after Marouane Fellaini’s header hit the crossbar.
The 30-year-old striker was delighted to secure three points for Louis van Gaal’s side at the home of their bitter rivals.
Rooney wrote on his Instagram page: “Massive 3 points for us today. Always great to win at anfield and delighted to score the winner!”
The England captain has discovered some impressive form in recent weeks after a return of four goals in his last three games in all competitions.
Rooney has scored six goals and has made two assists in 18 Premier League games so far this season.
The Red Devils are in fifth place and two points behind fourth-placed Tottenham Hotspur ahead of next weekend’s clash against Southampton.
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