Dutch destroyer Ruud Van Nistelrooy notched his 25th goal of the season as Manchester United turned up the heat on league leaders Arsenal with a seventh successive Premiership win.
Van Nistelrooy set United on their way to a 16th win in 19 games with the first of two goals in the space of seven first-half minutes as Sir Alex Ferguson's side blew Southampton away.
But it was UEFA Cup hopefuls Southampton who started brightly with midfielder Fabrice Fernandes and defender Michael Svensson both going close in the opening minutes.
Fernandes was desperately unlucky not to open the scoring five minutes in when his 20-yard sizzler was brilliantly tipped over the bar by United keeper Fabien Barthez.
Swedish international midfielder Anders Svensson should have scored less then a minute later when he shot into the sidenetting with only Barthez to beat after a Fernandes cross had opened up the United defence.
Svensson was made to pay for that miss on 14 minutes when the devastating van Nistelrooy hammered home his tenth Premiership goal of the season to put United ahead.
Van Nistelrooy expertly planted the ball into the corner of the net from six yards after defender Gary Neville and England captain David Beckham had combined down the right.
United doubled their lead just seven minutes later when Welsh international Ryan Giggs netted for the third time in two games.
Giggs slotted home at the second attempt after first being denied by a smart stop from Southampton goalkeeper Antti Niemi after Norwegian Ole Gunnar Solskjaer had crossed from the right.
But United's near perfect first half performance ended in disappointment when Barthez was stretchered off after colliding with striker James Beattie.
Southampton's misery was compounded three minutes from time when Finland international Antti Niemi joined Barthez in the St. Mary's treatment room after colliding with van Nistelrooy.