- Nathan Redmond's first-half strike enough to see Claude Puel's side take advantage in first leg clash.
- Philippe Coutinho returned after seven weeks out with an ankle injury, coming off the bench in the second half.
- Liverpool take on Manchester United at Old Trafford on Sunday.
- Jose Mourinho's eased to a 2-0 win over Hull City in the other semi-final first leg contest on Tuesday evening.
Full-time: Southampton 1-0 Liverpool
Lovren makes an important sliding challenge on Ward-Prowse who had two men waiting in the middle for his pass. Liverpool mount forward on the counter with Origi driving down the left, but as he reaches the byline the ball comes back off him and out for a goal kick. That should be that...
Coutinho drops a shoulder, cuts the ball onto his right foot and.... fires a wild effort over the bar. Southampton won't mind that. Just two more minutes for them to ride this out.
Four minutes of time added on at St Mary's.
James Milner just trapped the ball with his chin there. Outstanding.
Four minutes of the 90 left. It's all got a but anxious around St Mary's. Southampton have had plenty of chances to kill this off, but Liverpool could still bite back here.
Southampton denied a second ! Shane Long, just off the bench, races down the left to put Lucas under pressure and succeeds in doing so, robbing the Brazilian of the ball and cutting inside. He prods the ball across goal to Redmond who opts for the delicate chip, lifting it over Karius, but not under the crossbar. It bounces off the woodwork and Liverpool hack it clear.
Rodriguez is now shown a yellow card for hauling back Klavan. That will be his last action of the game with Shane Long coming onto replacing him. James Ward-Prowse also enters the fray for Steven Davies.
Coutinho has been Liverpool's best player since coming on but this time his effort on goal is a poor one, scooping a wild shot well over the bar.
Daniel Sturridge is handed a note by Klopp... but looks a tad puzzled after scanning it.
Coutinho again tries to dance his way through but Southampton defender resiliently. Romeu then gets the ball on the edge of his own box, shimmying past Lucas before winning a free kick for his side. Great play from the former Chelsea and Barcelona midfielder.
Pass it Cedric! The full-back makes a lung-bursting break down the inside right and into the box, where he is picked out by Tadic. Rodriguez is across him, waiting for a square ball to tap home but the Portuguese instead shoots, firing wildly into the side netting. Awful decision making there.
Coutinho drifts out to the left and darts menacingly into the box, drawing Yoshida out to make an important challenge. Already they look the more dangerous.
And here he is, Philippe Coutinho comes on for his first appearance since late November, replacing Wijnaldum.
Coutinho is now warming up to come on.
That will go down well at St Mary's. Adam Lallana winds back his left foot to shoot from range but screws a weak effort well wide of goal.
Daniel Sturridge has had an awfully frustrating night tonight. I think you could count the number of touches he's had all night on one hand.
Liverpool are looking sloppy and Southampton are looking dangerous on the break. Rodriguez is left to leave the charge on his own but does brilliantly to hold the ball up and wait for support from Tadic. He finds the Serbian but his cross is charged down.
Karius unconvincingly punches the ball away but the decision goes Liverpool's way. Goal kick.
From a tight angle, Tadic tries to bend one in the far corner but a Liverpool defender nuts it over the bar for a corner.
Milner just about drags the ball out of Cedric's path as the full-back makes a run down the right and he keeps the pressure on the Liverpool man, nicking the ball away before winning a free kick for his side on the edge of the box.
And Liverpool get us back underway for the second half.
Half-time: Southampton 1-0 Liverpool
Karius denies Redmond a second! It's terrible defending from Liverpool as Bertrand is allow to trot inside after a throw in and slide a ball into Rodriguez. He turns and slides it across the face of goal where Redmond is approaching, but his effort is saved instinctively by the Liverpool goalkeeper. It's a fine stop, but the Southampton forward really should have been looking for the far corner.