Spurs signed Sissoko in a deal worth up to £30million in the summer - equalling the amount they paid for Erik Lamela in 2013 - but the Frenchman has endured a difficult start to life at White Hart Lane.
Sissoko has made only four Premier League starts this term and Pochettino chose not to include him on the bench for his side's 2-1 defeat to Chelsea on Saturday.
He was also left out of the squad against West Ham last weekend, before coming off the bench against Monaco in the Champions League, and Pochettino insists it is up to Sissoko to prove his worth.
"Football is not about money," the manager told reporters.
"You [need to] show on the training ground you are better than another team-mate and you deserve to be involved.
"I need to take a decision and I believe the players that start on the bench deserve to be involved today in the game. It is not another thing to focus on."