Tottenham manager Mauricio Pochettino has been disappointed by club record-signing Moussa Sissoko, challenging the midfielder to show he deserves a place.
Sissoko, 27, joined Tottenham in a deal reportedly worth £30million from Newcastle United in August.
But the France international has made just six Premier League appearances - four of those starts - this season.
Pochettino, whose team suffered a 2-1 loss to London rivals Chelsea on Saturday, said Sissoko was yet to prove he deserved a spot.
"Football is not about money. It is about players being better and that they show on the training ground that they are better than another team-mate and that they deserve to be involved or not," he told UK newspapers.
"In my opinion, I need to take the decisions and I believe that the players that started in the game and the players on the bench deserved to be involved in the game.
"There's nothing else to it."
Sissoko was left out of the squad for the trip to Stamford Bridge, with Spurs seven points behind leaders Chelsea after the loss.
Pochettino called for the midfielder to show he deserved to be picked ahead of some of his team-mates.
"It's not frustrating for me. It's about football. We can see in football different things that happen. You sign a player and then you expect something, and you don't find what you expected," he said.
"If another deserved to be involved, like maybe Josh Onomah or maybe [Vincent] Janssen then why [Sissoko]?
"Because we pay money, do they deserve to play? He needs to work hard and to show in future that he deserves to be in the team."