SO much for the untouchables. Not for the first time under Rafael Benitez, Liverpool’s players boarded the coach out of Old Trafford harbouring pangs of regret.

Except on Saturday, they weren’t brought on by another defeat to their bitter rivals. Instead, it was simply because their margin of victory hadn’t been greater.

A historic occasion saw Liverpool make a mockery of Manchester United’s omnipotence as champions of England, Europe and the world with a result which could prove a defining moment in Benitez’s reign.

A biggest win at Old Trafford since 1936 inflicted United’s heaviest home defeat in more than 17 years, and was the ideal way for the Spaniard to rack up his 100th win as Anfield manager.

Coming just days after the routing of Real Madrid, only the Champions League triumph in Istanbul can surpass the high of the past week for Liverpool’s supporters during Benitez’s tenure.

It may almost certainly prove a futile gesture in this season’s championship race, but the long-term ramifications of this astonishing result could be significant.

Liverpool have sent out a message to the rest of the Barclays Premier League that United, far from being the untouchables Arsene Wenger professed they were, are beatable. Their air of invincibility has been shattered.

Perhaps United are not as good as people believe they are.

And perhaps Liverpool are better than most give them credit.

Certainly, while it will still take something remarkable for Benitez’s side to claim the title, United are now fully aware where the greatest challenge to their supremacy is likely to lay in the coming years.