Liverpool won 1-0 on Tuesday night thanks to Alexis Mac Allister's winner, with Carreras enjoying an impressive battle with Reds star Mohamed Salah.
The former Manchester United left-back said afterwards: "The feeling isn't the same as when you win. We came to a really tough ground tonight and we knew it was going to be a difficult game. In the end, the game was decided on a tiny detail. They scored from a set-piece, but they all count and it's given them the win.
“We still have to analyse the game. Perhaps we could have been a bit more aggressive, looking to play into the space, get forward quicker.
“I love a good duel. He has far more experience than I do - Salah is a Liverpool legend. You learn a lot from these battles, and I want to keep working hard to stop other guys like him."