Stuart Gray will tell you it was just three points and nothing personal - but he must have enjoyed putting one over Steve McClaren.
The former Manchester United number two turned down an approach by Saints in the summer, preferring instead to take charge at Boro, leaving the way clear for Gray to become Southampton boss.
This was their first meeting as managers, and it was Gray whose side had the better tactics, preparation, resolve - and players.
Boro were woeful. On this form, McClaren's magic touch could see them disappear from the Premiership!
But the fact is they were not given a sniff by Saints who recorded their biggest league away win in three-and- a-half years since the 4-2 victory at West Ham in April 1998.
For the first hour it looked a typical away display by Gray's men following their tried and trusted game-plan.
You know the one - keep it tight, score on the break three-quarters of the way through, and then hang on like fury!
However it turned out a little differently, and very encouragingly, as Saints coped with the Tranmere Factor!
This was their first serious test of character on the road since they squandered that 3-0 interval lead to lose 4-3 at Tranmere.
It was the first time since then that they had gone more than one goal up and then conceded.
James Beattie's first Premiership strike since February and a Marian Pahars' penalty seemed to have seen them home and dry, until Alen Boksic pulled one back from the spot.
But instead of wobbling under pressure to draw or even lose, they not only held firm but restored the two-goal advantage.
That was made all the sweeter by the fact that at the same time Glenn Hoddle's Spurs side were letting slip a three-goal lead to lose 5-3 at home to Man Utd - excellent preparation for next week's return to Tranmere in the Worthington League Cup!
That scoreline rounded off a perfect day for the 300 or so hardy travelling fans who must have feared a depressing return journey at half-time.
Dean Richards had scored on his debut for Spurs, and although Saints were level and in control of a dismal game, there were fears that yet again they might pay for their failure to to turn dominance into goals.
They had comfortably withstood the early pressure with Claus Lundekvam and Tahar El Khalej playing Alen Boksic with great intelligence.
They stood off at times to stop him turning and were backed up at others by good support from the midfield to close him down.
Matthew Oakley was commanding in midfield, and repeatedly got back to help out at the back. But even so was eclipsed by Chris Marsden.
His recall added much-needed bite to stop Boro coming through the centre, his awesome commitment in the tackle offering a big deterrent.
That provided the foothold for Saints to take charge, and they showed some nifty footwork as they cut through at pace, sometimes even being over-elaborate as they carved the home side open.
Beattie had the best chance when he ran clean through, held off Gareth Southgate but lifted the ball over the bar as well as the goalkeeper.
However he made amends on 66 minutes when Marian Pahars played in Wayne Bridge to reach the by-line.
He whipped over a cross, laying it on a plate for Beattie who timed his run to perfection to volley unmarked into the roof of the net from six yards.
Five minutes later, Saints sensed something special was afoot when they were awarded their first league spot-kick since April 1 last year.
They were the only side not to get a Premiership penalty last season, but that run finally came to an end when Pahars was tripped as he cut back sharply on Curtis Fleming who tripped him.
Pahars has always said if he is the one brought down, he wants to take the penalty. And he chased after the ball to ensure Beattie did not get there first.
It was the Latvian's first spot-kick for Saints and he dispatched it clinically into the bottom right corner sending Mark Schwarzer the wrong way.
It looked game over against a Boro side bereft of any attacking ideas and getting nowhere against a rigid and disciplined defence.
The only way they were ever going to score was a penalty or free-kick, and Wiley pointed to the spot as Szilard Nemeth tried to round Paul Jones who just clipped him.
Alen Boksic's spot shot was unstoppable, high into the top left corner to spark a furious onslaught for the home side.
It was a true test of character for Saints which brought Gray and Dennis Rofe to the touchline to repeatedly urge calm and clear-thinking.
To their credit Southampton steadied themselves and clinched the points with a neatly-worked third.
Former Boro boy Stuart Ripley must have enjoyed getting the better of Colin Coopper to square for Beattie to control and clip a perfect curling shot into the bottom right corner.
There were five minutes left - and the ground virtually emptied.
Home fans streamed out in their thousands leaving just a scattering as the game was played to a predictable and almost pedestrian conclusion against a backdrop of celebrating Saints supporters.
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