Southampton manager Ralph Hasenhuttl apologised to Arsenal counterpart Unai Emery after forgetting to shake hands amid the emotion of a late victory on his home debut.
The Saints ended Arsenal's 22-match unbeaten run and won their first home league game since April thanks to Charlie Austin's 85th-minute header with Hasenhuttl running on to the pitch to celebrate with his players on the final whistle.
"I had to run to my guys because they were waiting. I shook hands later and it was OK," said Hasenhuttl.
"It's what I wanted to feel when I came to the Premier League, this atmosphere after the game, and to celebrate such a moment is something very special for me."
In a see-sawing encounter, the hosts took the lead after 20 minutes as Danny Ings muscled home a header from Matt Targett's cross.
Henrikh Mkhitaryan nodded in shortly after for Arsenal, following good work by Alex Iwobi and Nacho Monreal - but Ings struck again just before the break.
Nathan Redmond's floated cross was precise and Ings cushioned a looping effort into the far corner.
Arsenal turned the screw in the second half and restored parity as Mkhitaryan's shot deflected in off Jannik Vestergaard.
The Gunners had their chances with Alex McCarthy impressing in the home goal, but Southampton were dangerous on the break and Shane Long had a goal rightly ruled offside before providing a teasing cross for Austin's winner.
The victory takes Southampton out of the relegation zone and up to 17th.
At the final whistle, Austrian Hasenhuttl - nicknamed the 'Klopp of the Alps' during his spell at previous club RB Leipzig - joined his players' on-pitch huddle before whipping up more decibels from the home support.
With rivals Chelsea winning away at Brighton, Arsenal are now three points adrift of the top four.