Then Arsenal, perhaps flushed at such an undeserved lead, simply went to sleep and allowed Southampton’s captain, Adam Lallana, to make it 2-2.
It was the type of casualness that has bedevilled Arsene Wenger’s side in the past, and one they have managed to dispel from their game for much of the season.
They had done the hard work but were pegged back, and in the end were hugely fortuitous to escape with a point after Mathieu Flamini was sent-off for a foolish two-footed challenge on Morgan Schneiderlin, albeit one his manager strangely defended afterwards
Indeed, it could be argued they were fortunate full stop. Bar a seven-minute spell at the start of the second half, in which they scored twice, this was comfortably Arsenal’s worst performance of the season.
They were out-passed, out-thought and out-fought by a hugely impressive Southampton side who were determined to show their recent blip was nothing more than that.
By the end, Arsenal had every man inside their own half for six nervous minutes of injury-time but they held on for a point — but both Manchester City and Chelsea could overtake them tonight.
That said, there is no shame in being outplayed by a Southampton side who have become many neutrals’ favourites this season.
Their season could have been thrown off course by a run of two wins in 11 games, the resignation of their executive chairman Nicola Cortese, or last week’s fight between club record signing Daniel Osvaldo and Jose Fonte.
Yet it has not been and after Fonte gave them the lead, they deserved this result. They enjoyed 69% of possession in the opening 20 minutes and Arsenal’s frustration was obvious as passes went astray and forward runs went unnoticed.
Mesut Ozil and Santi Cazorla, so often the metronomes of Arsenal’s play, were particularly guilty, but it would be churlish not to credit Southampton.
This was superb football from the hosts, who seem to have fully recovered from any fallout caused by the departure of their executive chairman earlier this month.
They created chances at will, with only a fine save from Wojciech Szczesny denying debutant Sam Gallagher early on.
And the goal came when Per Mertesacker was harshly punished for a foul on halfway, the ball was lofted to the back post and Fonte rose above Nacho Monreal to head home.
It should have been two when Gallagher shot wide from close range, but Saints were made to pay for their profligacy.
The sides were level two minutes into the second period as Olivier Giroud scored in his third successive away Premier League game, flicking home Bacary Sagna’s low cross.
The corporate seats in Southampton’s gleaming stadium were not yet filled and some had still not returned when Cazorla made it 2-1, cutting across the ball to send it curling into the far corner from Ozil’s pull-back.
There was pandemonium in the away end, but it lasted less than two minutes.
Sagna had outmuscled Jay Rodriguez for Arsenal’s equaliser but this was payback, the England international surging down the left and squaring for Lallana to smash home.
Arsenal came again and Ozil’s shot was deflected onto the crossbar, but Arsenal’s hopes of winning the game were laid to rest when Flamini was rightly dismissed by Lee Mason for his crude challenge on Schneiderlin.
From then on it was one-way traffic, but Arsenal held on thanks to fine saves from Szczesny from Fonte and Luke Shaw. At the end of the season this could be a valuable point.
SOUTHAMPTON: Boruc, Chambers, Fonte, Yoshida, Shaw, Cork, Schneiderlin, Rodriguez, Steven Davis (Do Prado 90), Lallana, Gallagher (Ward-Prowse 70).
ARSENAL: Szczesny, Sagna, Mertesacker, Koscielny, Monreal, Flamini, Arteta, Gnabry (Oxlade-Chamberlain 70), Ozil, Cazorla (Gibbs 86), Giroud (Podolski 90).