Five goals in a rampant first half earned Tottenham a stunning victory at St Mary's Stadium and ended the tenure of Southampton boss Russell Martin.

A strike inside 40 seconds from James Maddison settled any pre-game nerves for Spurs manager Ange Postecoglou, the England midfielder tucking home from Djed Spence's clever pass.

Against a woefully open Saints defence, Tottenham's free-scoring attackers cleaned up, Son Heung-min firing past Alex McCarthy and Dejan Kulusevski tapping in from close range inside the first 15 minutes.

Amid angry boos from the stands, Martin's response was to abandon his four-man defence and revert to a back three, withdrawing a distraught Kamaldeen Sulemana straight after the third goal.

And yet it did not work as a shell-shocked Southampton were hit on the break by Son once more and he teed up Pape Sarr to dance through two half-hearted challenges and slot into the net.

Spurs captain Son was denied three more times by McCarthy before Maddison smashed into the top of the net from a ridiculous angle deep into first-half stoppage time.

With Spurs fans delirious in the away end, some Southampton supporters took to the exits early, rightly anticipating little hope of a miracle comeback.

Matheus Fernandes did think he had pulled one back in the 80th minute but his header was ruled out for offside.

The result leaves Saints nine points from safety and guaranteed to be bottom at Christmas. Meanwhile, Tottenham are up to 10th, entrenched in a congested mid-table where just three points separate eight teams.