Ralph Hasenhuttl enjoyed a dream home debut as Southampton manager after Charlie Austin's late header earned a 3-2 win over in-form Arsenal.
Substitute Austin seized on a mistake by Gunners goalkeeper Bernd Leno with five minutes remaining to give the Austrian a perfect start at St Mary's.
Arsenal, whose 22-game unbeaten run came to an end on the south coast, twice equalised through Henrik Mkhitaryan following a pair of headers from Danny Ings.
The victory was Southampton's first in the Premier League on home soil since late April and prompted scenes of jubilation in the stands followed by a lap of honour on the pitch.
Hasenhuttl sent free beer vouchers to Saints' success-starved season ticket holders during the week in an attempt to have "everyone in our boat to row with us".
His gesture, combined with an energetic, hard-working display seemed to do the trick.
The 51-year-old, who replaced the sacked Mark Hughes on December 5, was greeted by a standing ovation ahead of kick-off.
And the noise levels increased significantly as Ings twice nodded in during an entertaining first half.
Armenia international Mkhitaryan gave the hosts a couple of reality checks with a brace of his own, but it was to be Saints' day after Austin pounced.
Arsenal manager Unai Emery was suffering a defensive headache so handed captain Laurent Koscielny his first league start since he suffered an Achilles problem in early May.
With Sokratis Papastathopoulos and Shkodran Mustafi banned, Emery also opted to deploy midfielder Granit Xhaka as a makeshift central defender on the left of a back three.
Playmaker Mesut Ozil, meanwhile, was left out of the Gunners' starting line-up for the fifth successive top-flight game, with Alexandre Lacazette joining him on the bench.
Southampton had won only one of 19 home league games dating back to November 2017, scoring just 16 times during that spell.
Hasenhuttl has insisted clean sheets are his initial priority, but his team were rewarded for their bright start and attacking intent with 20 minutes played.
Matt Targett swung in a superb left-wing cross and Ings - back from a hamstring problem - nodded powerfully past Germany international Leno.
The opening goal prompted a passionate celebration from Hasenhuttl, although he quickly cut it short after realising he had encroached into Emery's technical area.
His joy was short-lived though as Mkhitaryan headed Nacho Monreal's cross into the bottom right corner eight minutes later at the end of a well-worked moved involving Alex Iwobi.
Jan Bednarek then produced a last-ditch interception to deny Pierre-Emerick Aubameyang a tap-in.
Southampton's enthusiastic, pressing style was warmly received by their fans and they edged back ahead a minute before the break.
This time it was all about Ings as he directed a superb looping header into the right side of Leno's goal after Yan Valery lifted the ball into the area.
Emery reacted to the setback by introducing Lacazette in place of the injured Hector Bellerin at half-time and switching to a back four.
The changes had an immediate impact. Lacazette caught Oriol Romeu dawdling in possession just outside the Soutampton box, allowing Mkhitaryan to fire home from the edge of the box via a heavy deflection off Jannik Vestergaard which deceived Alex McCarthy.
Arsenal had not lost since August 18 but, after surviving a scare when Shane Long had a goal disallowed with 15 minutes remaining, their defence was once again breached.
Long burst away down the right-hand side and, after Leno came for his cross and failed to collect, Austin had the simple task of heading into the unguarded net to spark joyous scenes and move the club out of the relegation zone.