The league leaders trailed through Marcus Rashford’s opener but Lallana, among the unlikeliest of heroes, popped up with a crucial goal late on.
Rashford gave United the lead when he turned home Daniel James’ superb cross in the first half.
The goal was reviewed by VAR but Victor Lindelof’s challenge on Divock Origi wasn’t deemed to be a foul, and United led.
It seemed as though Ole Gunnar Solskjaer’s side were about to hand Liverpool their first league defeat of the season but they couldn’t hold on.
Lallana, introduced for Jordan Henderson in the 71st minute, scored the leveller when he converted Andy Robertson’s cross with five minutes remaining.
Liverpool missed Mohamed Salah but their supporting cast has made contributions time and time again.
And so it proved here, with Lallana scoring his first goal since May 2017.
The draw suits Liverpool fine - they remain six points ahead of second-placed Man City - but Klopp’s frustrations with VAR were evident.
He bemoaned to the fourth official after Rashford’s goal was allowed to stand and was upset when Sadio Mane’s equaliser before half-time was chalked off by VAR for handball.
And he made his feelings known after the match.
"They scored a goal that shows all the problems with VAR,” the German said.
“[Referee] Mr. Atkinson thinks he’ll let the game run because we have VAR. Then the VAR says ‘yeah there was contact, but you saw it differently.’
100% I see it like this. It’s a general problem.
Tell us how you really feel, Jurgen.
VAR was a major talking point on Saturday and it was another topic of discussion after its involvements at Old Trafford on Sunday.
It's clear that the Premier League hasn't quite figured it out just yet.News Now - Sport News