Almost an hour had drifted by with little to suggest Arsenal were serious about this late assault on the top-four when suddenly their two biggest stars came to life.
Mesut Ozil, flimsy and peripheral until this point, eased to his left on the edge of the box and opened his body in order to thread a first-time pass towards Alexis Sanchez as he exploded into the penalty box.
It was a fabulous example of Ozil's supreme vision, touch and appreciation of others around him.
Sanchez gathered the pass on the turn, shaped to shoot and chopped the ball from right foot to left, sending centre halves Maya Yoshida and Jack Stephens sliding across his field of vision in a blur of red and white.
With only Fraser Forster to beat, Arsenal's Chilean striker rammed a shot low past the feet of the Southampton goalkeeper.
In doing so he became the first Arsenal player to reach 20 goals in a Premier League season since Robin van Persie in 2011-12. Van Persie's goals fired Arsene Wenger's team into the Champions League that year and Sanchez may yet do the same.
Olivier Giroud came off the bench to score the second and victory lifts them into fifth, above Manchester United.
-Dailymail