For the first time in Premier League history, United trailed 4-0 at half-time and failed to score in a hopelessly one-sided contest. The Red Devils have now taken a run of one point from a possible 12 in the league. Naby Keita started the rout before Diogo Jota doubled Liverpool's lead inside 15 minutes.
Salah then took centre stage to take his tally for the season to 15 goals in 12 appearances and become the top-scoring African player in Premier League history in the process. To round off a miserable day for United, Paul Pogba lasted less than 15 minutes as a second-half substitute as he was shown a straight red card for a reckless lunge that forced Keita to leave the pitch on a stretcher.
Liverpool's first victory in front of a crowd at Old Trafford under Jurgen Klopp moves them back above Manchester City into second, just a point behind leaders Chelsea. By contrast, United's hopes of a first league title since 2013 already look over as they remain eight points off the leaders.
That gap is likely to grow in the coming weeks with Tottenham and City to come in the next fortnight before an international break. Whether Solskjaer will still be in charge come November is now in serious doubt as he has completely failed to form a balanced team from a talented collection of star players.
The Norwegian will wonder what might have been had Bruno Fernandes not fired over a glorious chance to open the scoring on three minutes. But soon the defensive cracks that have blighted United's season began to appear. Salah teed up Keita to open the floodgates after just five minutes with a composed low finish past David de Gea.
