A first-half strike from forward Nathan Redmond kept Southampton on course to reach their first League Cup final since Lawrie McMenemy’s Saints were defeated by Nottingham Forest, managed by Brian Clough at the time, in 1979.
“We cannot be happy with the performance and Southampton cannot be happy with the result,” said Klopp. “The best thing for us is the result. It could and should have been 2-0, 3-0.
“They had the biggest chances because we were not compact enough in situations and [goalkeeper] Loris Karius had to save our life. It’s a deserved win for Southampton but it’s only half time.
“In this moment I am not too happy with the performance after 1-0. The reaction was not good. The second leg will be a completely different game. Nobody should think it is already decided.”
Redmond himself admitted he “should have had four goals” and manager Claude Puel agreed that the tie should have been put beyond Liverpool with the second leg on 25 January rendered a mere formality.
“It’s a great performance but we are a little disappointed with the result with the many chances we had but it was important to win with a clean sheet,” said the Frenchman. “At the end we are unhappy with this result because we know the second leg will be very difficult.”
Liverpool beat Southampton 6-1 at the quarter-final stage of the competition last season but there seemed little chance of a repeat showing after a cagey opening to the contest.
The game, however, burst into life after 18 minutes as Saints’ goalkeeper Fraser Forster clawed away a Roberto Firmino volley, while moments later Loris Karius spread himself to thwart Redmond.
But the former Norwich flyer was not to be denied and slid the ball beyond Karius from Jay Rodriguez’s pass after Liverpool centre-half Ragnar Klavan had made a hash of a routine clearance.
Karius produced a reflex save to deny Redmond a second prior to the break, while 20 minutes after the restart rampaging full-back Cedric Soares lashed into the side-netting at the near post with Rodriguez lurking in front of goal.
Redmond was denied for a third time inside the final 10 minutes as his delicate chip clipped the underside of the crossbar after substitute Shane Long had bamboozled a wilting Lucas and played an intelligent ball across the penalty area.