Arsenal are used to getting the better of Southampton but last night it was the Saints who landed the killer blow.
The Gunners rested some key players, but started England international Jack Wilshere and £30 million signing Alexis Sanchez, who opened the scoring with a stunning free-kick.
Southampton put out a full strength team, knocking Arsenal out of the Capital One Cup at The Emirates, through a Dusan Tadic penalty and long range strike from Nathaniel Clyne.
The player who won the penalty was debutant Sadio Mane, a deadline day addition from Red Bull Salzburg who only received his work permit a matter of das ago.
Ronaldo Koeman said after the game: "We are happy we finally have Mane in, he brings competition to the squad, that's important, it's a long tough season."
That much is true, but Mane had attributes to offer of his own, troubling Arsenal defence with his speed.
He tired as the game went on, due to a lack of match practice which is to be expected, but he certainly layed his part in Southampton's first away win at Arsenal in 27 years.
Here's how fans reacted to his performance via Twitter:
Great half from the lads. Mané a real threat and for those who are not watching he is exactly what we've been missing. Sheer pace. #saintsfc— South Saints (@South_Saints) September 23, 2014
Mane is quality. Works hard and wins a fair few tackles too #saintsfc— McBendy (@_Firebirding) September 23, 2014
Mané looks solid. I like his pace and ability to win penalties. Great signing so far. #saintsfc— Tyler T (@tylertthinks) September 23, 2014