The England midfielder has become a crucial cog for club - and country - this season, whether under Frank Lampard or Thomas Tuchel.
Chilwell had worked with Mount at international level before his £45million move from Leicester to Stamford Bridge, but seeing the 22-year-old train day in, day out has shed a light on just how hard working the midfielder is.
"Before I came here me and Mason were close through England but I would only get to see him training and playing with him a few times a season," Chilwell said ahead of Chelsea's Champions League quarter-final second leg against Porto.
"Now, training with him every day and seeing how good he really is, not just his ability that he has that he was born with, his natural ability, but the fact that he works very hard, he is very keen to learn all the time, always doing extras, he’s always in the gym, doing everything he can to better himself.
"With the natural talent that he has, the work rate, the sky is the limit for him.
"This season, since I’ve come in to now, we’ve already seen he has improved so much. If he keeps on doing what he is doing, scoring, assisting, keeping humble, working hard away from the training ground, which I know he does, he will be a great player for Chelsea and England for a long time."
Mount has eight goals for both club and country across more than 50 appearances in all competitions this season and is a sure starter for Gareth Southgate when England begin the European Championship against Croatia in June.