Mauricio Pochettino has revealed Tottenham midfielder Dele Alli played all 90 minutes of Saturday's north London derby against Arsenal despite struggling with ankle and knee injuries.
The England international played a key role in the home side's second goal, scored by striker Harry Kane, during the 2-2 Premier League draw at White Hart Lane.
Alli had started the previous league fixture against West Ham on the bench before coming on as a second-half substitute, although he was unable to do anything to stop his team slipping to a 1-0 defeat.
Pochettino admits the club are taking care not to push the teenager beyond his limits as they enter a crucial stage of the season.
"He is an incredible athlete, yes, but he is not a machine," Pochettino said of Alli.
"He has a problem in his ankle and knee. He was good before the game but the players are not machines."
The former Southampton manager confirmed he is always monitoring the physical state of his squad, particularly with Tottenham still participating in Europe, too.
Tottenham travel to Germany to take on Borussia Dortmund in the first leg of their last-16 Europa League tie on Thursday. It will be the first of three games they play in the space of eight days, with the return fixture in London following on from a Premier League trip to Aston Villa.
"We have a lot of players who are young and in their first or second season in the Premier League," Pochettino added.
"It's very tough and we spend a lot of time analysing and to find information to give the best training sessions or recovery, or to find the best way to help them."