Mauricio Pochettino insists his Tottenham team selections cannot be considered "experiments" as he prepares to take on Newcastle United.
Spurs stole a 2-2 draw at Premier League champions Manchester City last weekend and face rivals Arsenal a week on Sunday, with struggling Newcastle visitors to the Tottenham Hotspur Stadium in between.
It was put to Pochettino that he might look to name a different XI against Newcastle in order to keep players fresh for the derby match, but he took issue with the word "experiment".
"Experiment? I'm not a scientist. I am not a chemist," he told a news conference. "You are talking about experimenting.
"That is in some room outside of this training room. We are coaches and we do our job, we don't experiment. We train people who have the ability to play football. Then that's it.
"Please don't compare us with doctors or people in university studying a lot. I have a lot of respect for the people who do what you say, experiment, to help life.
"But for us to find solutions, only I am a football coach, far away from the people who work in science or at university. I have full respect for them."
Discussing more openly the need to beat Newcastle, Pochettino still would not acknowledge there is pressure on Tottenham to win against a side in the bottom three.
"I think if we're going to talk about the extra pressure, it's a little bit early," he said. "We didn't feel the pressure of the Champions League final so, after our second game, we're not going to.
"Speculation is there, perception is there, I think we are going to try to play the game and try to win. Football is football and you have to respect your opponent. Newcastle are going to be a tough opponent.
"It's going to be a very difficult opponent. They need to start to win points, they'll be tough. They have a new manager, new signings. All that is going to make them more focused and try to be compact.
"For us, after a good result at City, our trust and confidence is high and at the same point believing Newcastle will be tough. We have to beat them."