Harry Maguire stunned Liverpool as his 84th-minute header clinched Manchester United's first win at Anfield since 2016 and condemned the hosts to a fourth consecutive defeat.
Maguire guided in Bruno Fernandes's cross just six minutes after Cody Gakpo had cancelled out a controversial opening goal from Bryan Mbeumo only 62 seconds into a thrilling contest.
Mbeumo beat Giorgi Mamardashvili from Amad Diallo's pass to leave Anfield shellshocked but Liverpool were furious play wasn't stopped for a head injury to Alexis Mac Allister, who went down in the build-up after colliding with Virgil van Dijk.
Mac Allister needed treatment and had to play on wearing protective headgear but VAR could not intervene as there was no foul. Guidance from the Premier League Match Centre suggested referee Michael Oliver did not stop play as he did not see the injury.
The dramatic opening set the tone for a pulsating game with Manchester United initially resisting Liverpool's efforts to equalise with the help of some luck. Gakpo struck the post three times before finally hauling the hosts level when he tucked home substitute Federico Chiesa's low cross.
The out-of-form Mohamed Salah had also missed two gilt-edged chances but it felt like Liverpool were primed to find a winner before Maguire struck to spark more jubilant celebrations from Manchester United, who might have had a second goal in the first half had Fernandes not fired wide from a big chance.
Liverpool tried to rally again in the closing stages but Gakpo missed a glorious opportunity, heading wide from Jeremie Frimpong's cross when it looked easier to score, leaving them to face up to a fourth consecutive loss for the first time since 2014, having also been beaten by Chelsea, Galatasaray and Crystal Palace.
A momentous victory for Manchester United means they have won back-to-back Premier League games for the first time under Ruben Amorim. It puts them only two points behind Liverpool in the table, with the champions four points off leaders Arsenal in third.
Skysports