Liverpool suffered a 1-0 loss to Southampton as Shane Long netted an injury-time winner to send Saints through to the final of the EFL Cup.
Liverpool needed to overturn their 1-0 deficit from the first leg, but a resilient Southampton performance saw the Reds fail to make the most of their home advantage.
Daniel Sturridge had chances, but his failure to convert them saw Saints hold out, before a fine counter-attacking goal safely secured their passage to Wembley.
Jurgen Klopp failed to guide Liverpool to a second consecutive EFL Cup final appearance
Liverpool player ratings against Southampton in EFL Cup semi-final second leg
Wed, January 25, 2017
Express Sport brings you Liverpool's player ratings from their EFL Cup semi-final second leg against Southampton
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Loris Karius – 6.6
Shane Long celebrates scoring the winner against Liverpool
But Jurgen Klopp reckons his side were unfortunate not to be awarded a penalty when the ball struck Long's hand inside the box as Roberto Firmino attempted an overhead kick in the final few minutes.
And when discussing the incident, Klopp decided to bring up their 1-1 draw against Manchester United earlier this month – when the Red Devils were awarded a controversial goal.
Klopp said: "The ref didn't see the handball of Long and it doesn't help in a game like this.
Jurgen Klopp congratulates Southampton at full-time
"If we could hear a referee's whistle it would be nice. I don't know how many times that has happened this season.
"Against Manchester United we had a clear offside goal [Zlatan Ibrahimovic], nobody says anything.
"Tonight a penalty, nobody says anything."
Liverpool now turn their attentions to the FA Cup with the visit of Wolves on Saturday (12.30pm).