The Saints were looking to sign off from top-flight football in style, but came up against a side they’d beaten in just one of the last 13 PL H2Hs.
They did themselves no favours in an effort to improve that dismal record, gifting Liverpool the opener inside 10 minutes.
As the hosts looked to play out from the back, Roméo Lavia’s errant square pass handed Diogo Jota one of the easiest goals of his career as he stroked into an empty net.
Liverpool's advantage was doubled moments later, as Roberto Firmino ghosted through the Saints’ defence before slotting under Alex McCarthy on his final appearance for the club.
Given their woeful form , a Southampton fightback looked beyond the realms of possibility, but with no pressure on their shoulders, Rubén Selles’ men produced a stellar response to falling two behind, levelling the contest before the break.
James Ward-Prowse halved the deficit, as the Saints skipper found space at the back post to stroke home into the far corner, before Kamaldeen Sulemana broke his scoring duck for his new side with a smart finish beneath Caoimhin Kelleher in the Liverpool goal.
Buoyed by their first-half comeback, Southampton completed a remarkable turnaround within three minutes of the restart.
After winning the ball back in their own defensive third, Sulemana sprinted from one end of the pitch to the other unchallenged before curling home from the edge of the area to double his personal tally.
The Liverpool backline was offering precious little protection to Kelleher between the sticks, and yet more slack passing allowed the Saints to make it 4-2.
Within two minutes of coming on, Adam Armstrong seized on a misplaced pass and surged away from the defence before slotting into the bottom corner in sublime fashion.
This topsy-turvy affair had another twist in yet though, as Liverpool stunned the St Mary’s crowd with two goals in as many minutes to level the scoreline.
Cody Gakpo slotted home a tap-in to reduce the arrears, before an emphatic strike from Luis Díaz restored parity for the Reds.
Cooler heads finally prevailed in the final stages as Southampton avoided defeat against the Reds for just the fourth time in the last 14 league meetings.
They drop down to the second tier after a titanic clash with UEFA Europa League bound Liverpool, who capped a disappointing season by failing to win for the 13th time on the road in the PL.
Flashscore Man of the Match: Kamaldeen Sulemana (Southampton)
