The Saints were 2-0 down with just 24 minutes on the clock, but roared back with their biggest goals spree since the New Year’s Day massacre of Chelsea.

Lee Clark’s deflected shot and Steed Malbranque’s stunning finish gave Jean Tigana’s men a big advantage early on – but Beattie, who had only scored once this season before today, struck from the penalty spot in the 26th minute.

His powerful header levelled at 2-2 after 41 minutes, and another display of aerial dominance after the break by the big front man clinched his treble and put Gordon Strachan’s men ahead.

Brett Ormerod swept home number four with 18 minutes left to leave Saints fans rubbing their eyes with disbelief.

Rory Delap was a late withdrawal from Strachan’s side just minutes before kick-off after complaining of feeling ill.

Tigana made another raft of changes, which included the return of Clark for his first start since his serious Achilles injury.

Southampton’s ex-Cottagers winger Fabrice Fernandes looked lively on the right flank, while England left-back Wayne Bridge was keen to attack on the opposite wing.

Fulham hit back and Clark capped his first start for seven months with the opening goal – thanks to a lucky deflection – in the 16th minute.

He burst forward and let fly from 22 yards, with the ball hitting Michael Svensson, wrong-footing goalkeeper Antti Niemi and flying into the corner of his net.

Fulham doubled their lead with 24 minutes gone, thanks to shocking Saints defending.

Steve Finnan was given time and space to screw a cross across the box – and Jason Dodd misjudged the delivery to allow Malbranque to sweep the ball home.

But the Saints reduced the deficit to a single goal two minutes later, thanks to referee Mark Halsey’s hand ball verdict against Alain Goma.

Brett Ormerod’s attempted cross hit the Frenchman’s arm at close range and Halsey promptly pointed to the penalty spot.

Beattie gave Edwin van der Sar no chance from 12 yards, thundering his shot into the top right corner.

And Beattie was on the mark again four minutes before the break, taking advantage of non-existent Fulham marking to powerfully head home Fernandes’ far post cross.

Fernandes gave a thrilling display of trickery three minutes after the interval, twisting Goma inside out to leave the Frenchman on the seat of his pants and shooting across the face of goal.

And that proved a sign of things to come as Beattie soared highest to seal his hat-trick with a fine header in the 52nd minute.

The big front man towered above Fulham centre-backs Goma and Zat Knight and van der Sar failed to keep his header out.

Fulham’s defence were looking decidedly shaky, with even the diminutive Brett Ormerod winning headers.

Tigana appeared to acknowledge his side’s problems at the back by hauling off Knight and putting Abdeslam Ouaddou on in his place.

But Fulham’s afternoon went from bad to worse in the 72nd minute when Chris Marsden burst into the Cottagers box.

Goma tackled him, but succeeded only in poking the ball to Ormerod, who joyfully side-footed under van der Sar to make it 4-2.