Liverpool dominated proceedings on a wintry Merseyside afternoon, but it was Louis van Gaal’s side who prevailed after Marouane Fellaini headed against the bar in the 78th minute and Rooney slammed home the rebound.
It was the England captain’s fifth goal in four games — the first time he has scored in four successive United games since March 2012 — and took his side to within two points of the Champions League places.
“Everyone knows the importance of this game — regardless of league positions, it is a massive football game and it is a great victory,” Rooney told Sky Sports.
“We needed the three points and to continue the start to this year, so it is a massive win for us.”
It was also Rooney’s 176th league goal for United, meaning that he has now surpassed Arsenal great Thierry Henry in terms of Premier League goals scored in the colours of one club.
“I didn’t know!” Rooney said when told of the record.
“It is great to have records, but scoring a winning goal at Anfield, it’s been a long time since that happened for me, so I will be a bit selfish today and enjoy that one.”