Liverpool made sure of the points six minutes later through substitute Jordan Henderson to seal an important win and maintain their title challenge.
In the second half it was looking like the Reds were going to have to share the points before Mo Salah and Jordan Henderson sent their side back to the top of the league with two late goals.
Naby Keita scored his first Liverpool goal but it was Mohamed Salah and Jordan Henderson who boosted the Reds' Premier League title hopes.
And fans gleefully welcomed back their hero at a crucial time for the club's season.
However, the equaliser arrived before half-time with Naby Keita picking the flawless moment to score his first goal for the Reds, heading past the reach of Angus Gunn.
"There's not many games left, any mistake can cost us".
Southampton started the evening just five points above the relegation zone at the other end of the table, but had won their past two games as part of a general upturn in form since Ralph Hasenhuttl took charge in December.
Although Virgil van Dijk ended Sunday's game against Spurs with an ankle problem he is set to be included in the Liverpool team.
There have been some breathtaking efforts from Salah - who also scored twice in the top flight for Chelsea in the 2013/14 season - since his arrival on Merseyside and we have picked out five goals that really caught the eye. "There have been so many late goals you think is their name on it".
"It was his first game for a while on that position and scoring a goal is a nice sign, absolutely".
He joyously removed his Liverpool jersey in celebration after beating Gunn in superb fashion - sending the Reds back to the Premier League summit.
Yet, on this occasion he chose the right option despite the presence of Roberto Firmino in support.
"I thought we showed great character in the first half".
"To make a difference and have an impact, that's what me and Milly wanted to do and thankfully we've done that and managed to win the game". "It was a big performance in the second half and a big result".