United crush Black Cats

Sir Alex Ferguson re-asserted his authority over talismanic former skipper Roy Keane as Manchester United maintained the pressure on Arsenal.

United cruised to a 4-0 victory at the Stadium of Light to leave Keane in little doubt as to the gulf in class between the teams at opposite ends of the Barclays Premier League.

United's victory was every bit as comfortable as the scoreline suggests as they cut through the Black Cats at will to expose goalkeeper Craig Gordon at regular intervals.

Goals from Wayne Rooney, Louis Saha and Cristiano Ronaldo before the break left the result in no doubt, and Ferguson was able to withdraw the hugely impressive Portugal international with more than half an hour remaining.

Saha rubbed salt into the wound with an 86th-minute penalty after Nani had been tripped by Danny Collins.

Keane knows the bulk of his side's points this season will not be taken from the likes of United, Arsenal, Chelsea and Liverpool, but from the sides in the battle for top-flight survival.

However, having seen them compete creditably in narrow defeats at both Old Trafford and the Emirates Stadium already, that was the very least he expected at the Stadium of Light.

What he got in the opening 45 minutes was graft and commitment, but what his players lack was abundantly clear as United, despite barely getting out of second gear, took them apart so comprehensively that damage limitation was the only thing on the minds of the bulk of a Boxing Day crowd of 47,360.

Despite leaving Ryan Giggs and Anderson at home and Carlos Tevez and Patrice Evra on the bench, Ferguson was able to field a side which had simply too much class, pace and guile for Keane's team, which included for the first time 17-year-old striker Martyn Waghorn.