Chelsea opened a six-point lead in the English Premier League football standings while Manchester United enjoyed perhaps their finest performance yet under Louis van Gaal with a 3-nil trouncing of Tottenham Hotspur.
Chelsea increased their advantage over Manchester City despite being held to a 1-1 draw at home against top-four hopefuls Southampton this morning.
Diego Costa opened the scoring for Chelsea in the 11th minute with a close-range header but Southampton deservedly equalised eight minutes later from a fortuitous penalty.
United, so often criticised for being slow and directionless under Dutchman Van Gaal, produced the most electric performance of the day, crushing Spurs with first-half goals from Marouane Fellaini, Michael Carrick and Wayne Rooney.
Chelsea, on 64 points, still have a game in hand on Manchester City, who were beaten at Burnley yesterday.
United, with 56 points, have climbed within a point of third placed Arsenal and two of their cross-city rivals City as well as moving five points clear of fifth-placed Liverpool.
Their win also seriously dents the Champions League qualifying hopes of Spurs who, on 50 points, are now behind sixth-placed Southampton on goal difference and struggling to keep alive their hopes of a top-four finish.
United produced a performance Old Trafford had been longing for as they blew fellow top-four chasers Spurs away with the pace, precision and directness missing so often in Van Gaal's unloved reign.
Fellaini, released by Carrick's intelligent through ball, put them ahead after nine minutes with a sweet left-foot strike, before Carrick headed home from distance 10 minutes later after the excellent Fellaini had wrought more havoc.
Rooney's bustling run and cool finish after 34 minutes provided the knockout blow.
In this morning's other game, Everton eased pressure on manager Roberto Martinez with their first home league success in three months with a 3-nil win over 10-man Newcastle United.
Newcastle had Fabricio Coloccini sent off just before the hour for a foul on Aaron Lennon.
It was Everton's second win in their last 13 Premier League matches.