Jose Mourinho's side now have a five-point gap over 3rd placed Liverpool thanks to Rashford's goalscoring heroics.
Liverpool's much-vaunted forwards made it easy for United, though, because none of them was prepared to drop deep and go in search of the ball. Trent makes this move and then he cuts back and then there needs to be another player.
Ten minutes later, Lukaku was again instrumental.
On both occasions the Belgian bullied Dejan Lovren to win long balls forward.
Everton beat Brighton 2-0, while Swansea drew 0-0 at Huddersfield despite having Jordan Ayew sent off.
An Eric Bailly own goal gave the visitors hope, and three penalty claims of varying legitimacy offered a grievance, but United was largely unfazed by a Liverpool attacking trio that ranks among the Premier League's most fearsome: Mohamed Salah was largely rendered an irrelevance; Roberto Firmino, so key to Liverpool's attacking intentions, was starved of space and time; Sadio Mané was driven into ambushes.
Was not at fault for either goal and had very little to do otherwise, except a couple of punches from crosses and corners.
Barnett suspended for opening round NCAA Tournament game
A one-week punishment would leave Barnett eligible to return for the second round on Sunday should the Tigers advance. Barnett won't play against FSU but will be allowed to practice this week and travel with the team to Nashville.
For the second, Lovren actually got his head to the ball off De Gea's kick but stumbled to the ground under pressure from Lukaku, who collected possession and fed Juan Mata.
One fan even referred to Lovren's bad performance as "groundhog day", suggesting he is prone to a bad performance just as he looks like he's finding some consistency in Liverpool colours. Liverpool pushed us back but I don't remember the chances that need David de Gea to make the goal safe. "He keeps in contact with us and let us know where we are at".
Matt Ritchie made it 3-0 just before the hour to lift Newcastle to 13th place while Southampton remain 17th, just a point outside the relegation zone with rivals Crystal Palace and Stoke holding a game in hand.
Liverpool had to be patient with the clock ticking on, and the Reds had arguably their biggest penalty shout of the match when Mane was brought down by substitute Marouane Fellaini, but nothing was given. We had enough chances to win but it is not enough when you concede.
"In the second half we chased the game which against a team like Manchester United is really hard". Yes, his double strike in the 2-1 win vs.
'With the yellow card and the pressure of Gary, I chose to make a change and bring a player on who could make a foul'.
"Jurgen Klopp will be raging because if you can't defend a punt up the pitch, a 70-yard punt, you're in trouble". In the second half we didn't want to be as defensive as we were.