Jay Rodriguez scored twice, with Rickie Lambert and Adam Lallana also finding the net, to help Southampton cruise to victory in front of the watching England manager Roy Hodgson at St Mary's on Saturday.
Reserve Newcastle goalkeeper Rob Elliot, in for the injured Tim Krul, produced a string of outstanding saves in the first half, but his efforts proved in vain in a dismal showing from the rest of the Newcastle side.
Alan Pardew started his four-game touchline ban following the end of his three-match stadium suspension for headbutting Hull City's David Meyler earlier this month.
But the Newcastle boss will have been thoroughly disappointed with what he witnessed as Lambert set up Rodriguez for the opener in first-half injury time, before then converting a Lallana delivery shortly after the break to effectively ensure Southampton's victory.
And the win was rounded off as Lallana netted with a stunning long-range strike and Rodriguez coolly powered home his second in the closing stages to cap a wonderful display from Mauricio Pochettino's men.
Elliot saw his goal threatened three times in the early going by Rodriguez, who missed a glaring opportunity after breaking free of the Newcastle defence, before then heading wide from a Calum Chambers cross.
Rodriguez did eventually produce an effort on target with a low header, but was thwarted by a fine diving save from Elliot.
That stop clearly boosted Elliot's confidence and he again came to the rescue after 15 minutes with an excellent one-on-one save from Lambert.
Southampton continued to waste opportunities, with captain Lallana somehow heading wide from point-blank range after Chambers had knocked a clever ball from Lambert into his path.
The hosts' dominance was evident in every facet of the game, with only Elliot, who produced a marvellous stop shortly before the break to again deny Rodriguez, keeping the scores level.
The former Burnley striker looked to have the goal at his mercy from a Lambert flick-on, but Elliot displayed remarkable reflexes to keep the ball out.
However, Elliot was finally beaten in first-half injury time as Rodrgiuez slotted home a simple finish after Lambert had sprung the visitors' offside trap.
Newcastle made two changes during the interval, Davide Santon and Luuk de Jong replacing Mapou Yanga-Mbiwa and Hatem Ben Arfa.
But those alterations had little impact and Southampton doubled their lead just four minutes into the second half when Lambert rattled home Lallana's right-wing cross at the far post.
The visitors were lucky to keep 11 men on the field following a rash challenge on Jack Cork from Papiss Cisse, but their misery was soon compounded by Lallana and Rodriguez.
First, Lallana picked up the ball in midfield, surging forward before unleashing a vicious long-range effort that flew past Elliot into the top corner, before Rodriguez emphatically converted Gaston Ramirez's ball over the top of the Newcastle defence a minute from time.
