It's been a thrilling week so far for the Reds, after they eased into the Europa Leauge quarter finals, drawing 1-1 at Old Trafford to make good on the 2-0 lead they had established at home to Manchester United, just a week earlier.
Philippe Coutinho will be full of confidence after his superb solo goal sealed progression, setting up a meeting against Borussia Dortmund in the last eight, securing a reunion for Liverpool boss Jürgen Klopp.
Liverpool in with a shout of the top four?
Attentions must now turn back to the Premier League, as Klopp's men look to continue fighting their way back into the top four chase. Despite having not played any league football for two weeks, excitement has been gaining pace over the chances of Liverpool fighting their way into the top four, mainly thanks to those impressive European performances.
However, Klopp has overseen three consecutive league victories, away wins over Aston Villa and Crystal Palace sandwiched by the home thumping of Manchester City, leaving the Reds just seven points from fourth with a game in hand.
So, with that in mind, a win over the Saints would be a welcome boost, on a weekend where many of those around them face tough games.
Saints will provide a tough test
One problem for Liverpool is the opposition that they face on Sunday, with Southampton harbouring European aspirations of their own, hoping to get into next season's Europa League.
Although the Reds have two games in hand, Southampton are currently above Liverpool on goal difference, and hold some hope of finishing in the top seven, following some impressive recent form.
Following a dismal Christmas period, Koeman's side surged up the table in January and February, at one point going six consecutive games without conceding. They've been slightly less consistent recently, winning three, losing two and drawing one of their last six, but they'll still fancy themselves to get a positive result.
It's likely that three former Saints will line up at their old ground on Sunday, with Nathaniel Clyne, Adam Lallana and Dejan Lovren all expected to start for Liverpool. Lovren, who left following a long-running saga, is likely to get the worst reception, but he'll be confident after some much improved recent performances.
Elsewhere for Liverpool, James Milner is out through suspension after being sent off against Palace, meaning an opportunity may open up for Joe Allen to get into the team. This would be made more likely should captain Jordan Henderson fail to start, the skipper was taken off against United after vomiting at half-time.
Alberto Moreno faces a race to be fit after pulling up in training on the eve of Thursday's European tie, meaning Jon Flanagan could appear, whilst it remains to be seen whether or not Daniel Sturridge will play two games in four days, with Divock Origi snapping at his heels for a start. It's worth remembering that the Belgian hit a hat-trick at St Mary's earlier this season, in a 6-1 Capital One Cup win.
Southampton were given a large boost when Saido Mane had his suspension for a red card against Sunderland overturned, meaning he'll feature. The forward scored a late equaliser when these two teams met at Anfield earlier this season, in Klopp's first home league game.
Elsewhere for the hosts, defensive midfielder Victor Wanyama is back available after completing a five match suspension. Captain Jose Fonte is also back after a ban of his own.
Potential Liverpool XI: Mignolet; Clyne, Lovren, Sakho, Flanagan; Can, Henderson; Lallana, Firmino, Coutinho; Origi.
Potential Southampton XI: Forster, Martina, Fonte, Van Dijk, Bertrand, Wanyama, Romeu, Davis, Tadic, Mane, Pelle.