Monday's victory against title rivals Manchester City continued the Gunners' 100 per cent record in December, strengthening the belief that this could finally be the year they once again win the title.
However, the wait to add to their 2004 triumph could well continue if the Boxing Day defeat to Southampton is anything to go by as Ronald Koeman's men ended a six-match winless streak by romping to victory on a blustery Boxing Day evening.
Martina was the unlikely catalyst to Saints' first win since November 7, with the full-back marking his first Premier League start with an exceptional strike with the outside of his boot from distance.
Offside calls against Steven Davis in the build-up were ignored, as was Laurent Koscielny's appeal for a foul in the build-up to Shane Long's close-range strike 10 minutes after half-time.
Jose Fonte's header and another Long effort late on added extra gloss to the scoreline on a night when Saints' response to recent disappointments was as marked as Arsenal's collapse.
Southampton made four alterations for the north Londoners' visit and changed tack following last week's loss to Tottenham, starting at a slower, more methodical tempo as they looked to firm up at the back.
Olivier Giroud headed over and a bobbling Nacho Monreal shot were the visitors' only attempts of note early on, with Saints' first shot coming in the 19th minute - and what a strike it was.
With offside calls against Davis ignored, the ball eventually fell for Martina and the full-back unleashed an exquisite half-volley from 25 yards with the outside of the boot that flashed past Petr Cech.
Koeman jumped off his bench in disbelief as much as celebration and James Ward-Prowse attempted to extend that advantage, dragging wide and then curling well over.
Davis was unable to connect with a snapshot and Long saw a goal chalked off for barging Per Mertesacker in the build-up, with a booking irking the Ireland forward further.
Arsenal attempted to capitalise as Theo Walcott forced the returning Maarten Stekelenburg into a save, before the inexplicably-unmarked Southampton academy graduate headed wide from a corner.
The Gunners were beginning to knock on the door but Saints threatened to snatch a second before the break, only for Long to lift well over the crossbar after meeting Sadio Mane's clipped pass.
Southampton did, though, find the net again five minutes after half-time, with Virgil van Dijk heading home Ward-Prowse's free-kick under pressure.
The celebrations were short-lived thanks to the offside flag, but St Mary's soon erupted again and there was to be no halting the revelry this time.
Long led the Saints break and played the ball out wide to Mane, continuing into the box where he met the Senegalese's pass with a low shot past Cech.
Arsenal players were furious with referee Jon Moss for allowing the goal as Koscielny tumbled under pressure from Long in the build-up.
Things would get worse for the visitors in the 69th minute
Saints captain Fonte ghosted in at the near post to nod home a Ryan Bertrand corner, leading a number of the visiting support to head for the exits.
Dusan Tadic forced Cech into action as the home side looked to add extra embarrassment, with Long hitting the post in the 89th minute after flashing past the cumbersome Mertesacker.
Things would get worse in stoppage-time, though, as Long collected Tadic's pass and slotted through Cech's legs.
TWEET OF THE MATCH
@GaryLineker: "Martina should be fined for attempting that
As it turns out it could be goal of the season
Maarten Stekelenburg: 7 (out of 10)
Cuco Martina: 8
Virgil van Dijk: 8
Jose Fonte: 8
Ryan Bertrand: 8
Jordy Clasie: 8
Victor Wanyama: 8
Steven Davis: 8
James Ward-Prowse: 8
Sadio Mane: 8
Shane Long: 9
Oriol Romeu: 6
Dusan Tadic 7
Petr Cech: 5
Hector Bellerin: 5
Per Mertesacker: 4
Laurent Koscielny: 4
Nacho Monreal: 6
Mathieu Flamini: 5
Aaron Ramsey: 6
Joel Campbell: 5
Mesut Ozil: 6
Theo Walcott: 6
Olivier Giroud: 6
Alex Oxlade-Chamberlain: 6
Calum Chambers: 5
Alex Iwobi: 6
Shane Long - In for the injured Graziano Pelle, the Ireland international shone in attack
Proved a nuisance from beginning to end, he netted twice and hit the post late on
The performance certainly gives Ronald Koeman a welcome selection headache.
MOMENT OF THE MATCH
Cuco Martina's first Premier League start brought with it a goal-of-the-season contender
Meeting a bouncing ball on the half-volley, his curling shot whizzed past Petr Cech from 25 yards.
VIEW FROM THE BENCH
Arsenal manager Arsene Wenger named an unchanged side at St Mary's, whereas Southampton counterpart Ronald Koeman made four alterations - two of which enforced with Pelle and Cedric Soares injured
It was the introduction of Shane Long in attack with Sadio Mane that was key here, with the pair running riot against Arsenal.
MOAN OF THE MATCH
This was an embarrassing loss by any standards, but the number of Arsenal fans leaving straight after the third goal was striking
There are no London-style traffic problems in Hampshire that can be used as an excuse.
WHO'S UP NEXT?
West Ham v Southampton (Barclays Premier League, Monday December 28)
Arsenal v Bournemouth (Barclays Premier League, Monday December 28)
Arsenal boss Arsene Wenger was quick to praise opponents Southampton for an impressive display.
He told BT Sport 1: "We lost too many challenges, they were sharper than us and we were a bit unlucky as well
I think the first goal was the first shot on goal and it found the top corner and I think the second goal was a foul on (Laurent) Koscielny, but the ref didn't see it and after that we were exposed on the counter-attack.
"It's a disappointing result, but you have to say well done Southampton.
"Many challenges we were second best, but the referee let a lot go as well and when you are not dominant that's the kind of price you have to pay.
"I've said many times, it's down to consistency to fight in every single game and find the resources to produce a top-level performance in every single game.
"Today was a very, very, very physical game and you could see this team, they tried for life and when they scored the first goal you could see it was going to be a very difficult game."
Martina, who had not played for Southampton since September, was a man of few words when asked about his wonder strike on BT Sport 1, saying: "Yes, it was a great goal, but...what a feeling
It's crazy to say, but it was a good shot I think.
"I got given my chance and I wanted to prove myself, that I could play."
Striker Long said of Martina: "He's been brilliant in training, he's been really working hard to break into the team and he deserved his chance today
I said it to him yesterday and he took it really well I thought."
Source : PA