Nathan Redmond's fine first-half goal gave Southampton a 1-0 win over Liverpool in their League Cup semi-final first leg at St Mary's on Wednesday, but the tie remains in the balance after the hosts squandered a series of chances.
The Saints were deserved winners against a disappointing Liverpool side, who did far less with the greater share of possession.
Poor finishing from Southampton, however, and a rehabilitating performance in goal by Liverpool's Loris Karius left everything to play for in the second leg at Anfield in two weeks' time.
The Saints took the lead against a subdued Liverpool when Redmond darted onto Jay Rodriguez's through pass to steer the ball right footed past the advancing Karius in the 20th minute.
The hosts failed to add to their advantage, however, and a number of opportunities went begging, including two more for Redmond.
"We were in good shape when we started (the match) but our reaction (to going behind) was not good," Liverpool manager Juergen Klopp said.
"We lost our timing... It will be a completely different game (at Anfield), tonight we weren't good enough. It was a deserved result (for Southampton)."
Only a minute before the goal Karius, who had been dropped after Liverpool's 4-3 league defeat at Bournemouth last month, blocked a shot from Redmond with his foot.
The winger then failed to convert another opportunity shortly before halftime with a shot from his weaker left foot that the young German goalkeeper leapt to push away.
Southampton always looked the more likely to score and they were denied by the woodwork five minutes from fulltime when Redmond chipped Shane Long's cross to the far post onto the bar before it was cleared.
Early first-half pressure from Liverpool almost delivered them a goal, but Fraser Forster tipped a shot from Roberto Firmino over the bar.
Brazilian playmaker Philippe Coutinho came on for the last half hour in his first appearance since sustaining an ankle injury in November but looked rusty and failed to spark the improvement Klopp had hoped for.
"We were strong together and had a very good spirit," Saints manager Claude Puel said.
"It was a good performance, it was important to win and with a clean sheet. I think Liverpool had only one chance in the first half. We were strong together in defence and kept the ball and had good counter-attacks."
Manchester United beat Hull City 2-0 in the first leg of their semi-final at Old Trafford on Tuesday.