Arsenal triumphed 2-0 on the south coast tonight against Southampton to keep their slender Champions League qualification hopes alive.

Second half goals from Alexis Sanchez who showed quick feet and a calm head, and substitute Olivier Giroud saw the Gunners pick up all three points against an attacking home side.

The result was only marred by Alex Oxlade-Chamberlain forced off on 35 minutes due to a muscle injury that will be assessed before Saturday’s visit to Stoke City.

Arsenal defender Laurent Koscielny missed out tonight through a calf injury as Shkodran Mustafi took his place, with Petr Cech assuming the captaincy.

Granit Xhaka started despite aggravating a shoulder injury against Manchester United.

Southampton had no new injury concerns ahead of manager - and Wenger protégé – Claude Puel, although Arsene’s former Monaco player was quoted a saying fatigue was a factor for his team.

The prolific Charlie Austin was nearing a return after five months out with a dislocated shoulder, while Matt Targett could also feature before the end of the season – but neither made the bench for this evening’s match.

With the match being a must-win for Arsenal, extra spice was added by the fact Arsenal had failed to win a league fixture at St Mary’s in 14 years - five attempts since 2003 with two losses and two draws..

The Saints also had the chance to clinch three consecutive home league games against Arsenal for the first time in 32 years if they clinched a victory tonight – even if the South Coast outfit have won just six of their 35 Premier League meetings with the North Londoners, losing 19 matches.

Saints were winless in their previous four matches – and a fifth match in a row without victory would have signalled their worst run of the season.

Arsenal for their part had lost five of their last six away league games – which is as many defeats as they endured in their previous 27 matches – with only one clean sheet in their last 13 away fixtures.

They had also won a meagre three points from a possible 27 away to sides in the current top 11.

As the atmosphere crackled at kick off in the late evening sunshine something had to give in this crucial match for the Gunners - we were soon to find out what it would be.

An enterprising if shapeless opening nine minutes was punctuated by Ryan Bertrand flashing a shot past Cech’s post.

Six minutes later Alex Oxlade-Chamberlain drew four players in the box before feeding Aaron Ramsey who curled a low shot narrowly past Forster’s left hand post.

Arsenal were fortunate to be fall behind on the half hour as an excellent block by Cech from Manolo Gabbiadini saved the team after ball fell to him following last ditch challenge from Mustafi on Tadic.

It was a real let-off for the Gunners even if Gabbiadini – who registered four goals in his first three appearances for Southampton - had failed to score in his last five, managing just one shot on target in the process.

Oxlade-Chamberlain then succumbed to what appeared to be a muscular injury with ten minutes remaining in the first half as he was replaced by Hector Bellerin.

There had been concern voiced beforehand about whether two matches in four days would be too much for the former Saints player.

With the ‘Ox’ making seven assists in the league this campaign - as many as he created in the previous five seasons, and excelling in his new role with important games to come there will be concern about the length of his absence.

The game had fallen into a lull until Nathan Redmond unleashed an accurately placed 30 yard shot at the visitor’s goal.

With the ball heading just inside the apex of post and bar Cech – following on from his superb shot stopping in the North London derby - tipped the ball past the post.

There was still time for Welbeck to narrowly fail to get on the end of a deep cross from Bellerin as the break approached.

But as referee Jonathon Moss blew for 0-0 in an absorbing game, it was Saints who shaded it on points.

The game started in much the same vein with plenty of endeavour and attacking intent - but obduracy from both backlines prevented penetration.

As doubts were starting to rise about whether a stalemate tonight would effectively end Arsenal’s league season Sanchez and his quick feet led the Saints defence on a merry dance before he rolled the ball past a wrong footed Forster.

He then proceeded to run towards the travelling support before he and his teammates celebrated wildly in joyous relief.

As the clock ticked down Puel made a double change with Soufiane Boufal and Shane Long coming on for Ward-Prowse and Redmond in the 69th minute. Memories were jogged regarding the two promising seasons with Lille before the 23-year-old was snapped up by Puel last summer before many other clubs took the plunge on him.

He quickly showed just why he was so highly rated by jinking through a packed Gunners backline, but just as he worked valuable space his shot was high and wide.

Wenger then sent Olivier Giroud on for Welbeck who worked hard tonight, as Puel replaced Tadic with Jay Rodriguez on 79 minutes. It was to be the Arsenal substitute who was to make his mark as three minutes after coming on Giroud header past Forster to make it 2-0 following a well directed nod from Ramsey on the byline.

In truth, despite Saints attacking intent the score was a fair reflection – as Arsenal took their chances and Southampton didn’t.

The race for fourth spot is still on. Just. Stoke City await.

Southampton: Forster, Cedric, Yoshida, Davis, Tadic (Rodriguez, 79), Romeu, Ward-Prowse (Boufal, 69) Gabbiandini, Bertrand, Redmond (Long, 69) Stephens

Arsenal: Cech, Gibbs, Sanchez, Ramsey, Ozil (Coquelin, 88), Oxlade-Chamberlain (35, Bellerin), Holding, Monreal, Mustafi, Welbeck (Giroud, 79) Xhaka.

Referee: Jonathan Moss