The match was marred by the first-half red card for Javier Mascherano, after his protracted dissent in a confrontation with referee Steve Bennett.

Many suggested Sunday's dismissal was a product of the Ashley Cole incident in midweek at Spurs - when the Chelsea star showed dissent, and his back, to referee Mike Riley but received only a yellow card.

Bennett was the fourth official on the touchline at White Hart Lane that night.

It has emerged, however, that the root cause of Liverpool's anger and frustration at Old Trafford was the treatment meted out to Torres by United defenders.

Torres was taken off near the end - according to Reds boss Rafael Benitez, "to protect him", with the game already lost.

Wes Brown scored in the first period, with Cristiano Ronaldo and Nani adding late goals for the champions.

It was a great day for Sir Alex Ferguson's men, who are now five points clear at the top - following Arsenal's defeat at Chelsea.

But Benitez must now pick up the pieces before Sunday's Merseyside derby with Everton, whom Liverpool lead by two points in the race for fourth spot.

Mascherano will miss that match, serving a one-match ban.

Benitez said: "Torres had some knocks on his ribs and ankle - a lot of knocks and a lot of kicks. I was just trying to protect him. The doctors will do a scan, and we will see.

"Was I disappointed by intimidation of Torres? Maybe I should ask others for their opinion. I have my own opinion, which was very clear.

"We have seen a lot of things and we do not need to talk about problems with referees. It was very clear."