The visitors won a tense quarter-final 5-4 in the shoot-out having finally levelled Darren Anderton's opener with only five minutes left of normal time.
Midfielder Gus was the first player to miss from the spot when Mark Schwarzer read his intentions and saved to his left.
That left Gaizka Mendieta to clinch it but Kasey Keller produced a fine low save to level it up again.
But the joy around the stadium soon turned to pain when 'Tano' sent Schwarzer the wrong only to see his spot kick come back off the post.
That left Franck Queudrue to wrap it up and he did so in style.
A crestfallen Gus reflected: "When you go into penalties you know someone has to miss. I've never seen a shoot-out go on for days, so someone will miss, someone will score, it will be over.
"Nobody wants to be that player. I'm very disappointed and very sorry for everyone because we worked hard and Kasey was magnificent.
"I just wanted to see if the keeper would move. Maybe I played too safe. Kasey then saved Mendieta's penalty and I was so pleased, I thought we would come back but unfortunately Tano then missed.
"Tano is really upset because he knew what he wanted to do, send the keeper the wrong way and place it the other side but hit the post. It's quite hard to take.
"This happens. I will be hard on myself. I will have a couple of bad days now but all you can do is keep going."
Gus Poyet expects to suffer 'a few bad days' after his penalty shoot-out agony in last night's Carling Cup defeat against Middlesbrough.