Mauricio Pochettino refused to guarantee first team places to Chelsea's big money signings after the club's spending since last season reached £350 million ($440 million).
Southampton midfielder Romeo Lavia completed his £53 million switch to Stamford Bridge on Friday as the club's shopping spree showed no signs of abating.
The Chelsea have made eight signings since the Argentine took charge in the close-season even though Pochettino has expressed a desire to trim the club's already bloated squad.
Moises Caicedo was signed from Brighton for a British record £115 million on Monday to bolster Chelsea's midfield options.
With the highly-rated Lavia on board as well, Pochettino knows he will be expected to unleash a new-look side when Chelsea travel to London rivals West Ham on Sunday.
But, despite the club's financial outlay, Pochettino wants his new recruits to prove they are worth a place in his plans.
"The players have a clear idea that they need to compete for their place and then it's the coach that is going to decide who are the best for every single game," Pochettino told reporters on Friday.
"It's not that if we sign a player and we spend big money, that they are sure to play. I don't tell Moises or Lavia 'you are going to play, whether you are good or bad'. It's not like this, football.
"Talented players, players that the club spends money on, they need to show every day that they deserve to play.
"My job is to be fair with everyone in the squad. You sign a player on an eight-year contract and after that he doesn't run, is not involved, no commitment - is he going play? That is our job. It's our judgement.
"I have the support of the owner, I have the support of the sporting director, so far. They need to trust in our judgement. It's not the people of social media, it's our judgement."
Chelsea have pursued a policy of awarding unusually long contracts under the ownership of Todd Boehly's Clearlake Capital consortium, with deals of between six and eight years commonplace at the club.
Pochettino was asked how easy it would be to get rid of players on lengthy deals who are unwilling to work for their place in the side.
"If you have an eight-year contract, you need to be responsible," he said.
"Players need to show respect, need to show commitment, need to show the performance that we expect from them. If not, they're not going to play.
"The player cannot be upset. If we sign a player and give an eight-year contract and then the player is not going to do what we expect or what he needs to do and then he doesn't play. It's because of him, not because of us."
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