The 24-year-old Spence has found his stride in Ange Postecoglou's injury-hit squad over the past two months.
He helped keep the holders at bay in January's first-leg win and now aims to help his side reach the final on Wednesday (Thursday AEDT).
Tottenham have suffered repeated blows to their backline with Radu Dragusin likely out for the season due to an ACL injury, while defenders Cristian Romero, Destiny Udogie and Micky van de Ven are also sidelined.
"I back myself against anyone. (Salah) is a great player and he is in good form but you have just got to nullify what he's good at really," Spence told reporters on Tuesday.
Salah, 32, leads the Premier League top scorer list with 21 goals, two ahead of Manchester City's Erling Haaland.
Spurs were left with one win in 11 league games before bouncing back in the Premier League with a vital 2-0 win at Brentford on Sunday.Â
Ange Postecoglou is trying to take Spurs to the League Cup final but Liverpool stand in their way. (AP PHOTO)
Pressure is mounting on Postecoglou, with the north London side sitting 14th in the league standings.
"It's been difficult but we fight for the manager, we fight for the club and you know, we all believe in what he wants to do," Spence added.
Spence said confidence would be key to turning Spurs's fortunes around.
"We have got to be confident and we have got to be ready to fight and hopefully we make it to the final."
In the other semi-final, Newcastle hold a 2-0 advantage over in-form Arsenal.
They will meet at St James's Park after the Gunners were stunned by goals from Alexander Isak and Anthony Gordon in the first leg in London.
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