Mourinho signed centre-back Zouma in 2014 during his second spell in charge at Stamford Bridge.
The Frenchman had been in the Saint-Etienne senior side for three years after graduating from their youth system, but he was still only 19 when he moved to west London.
Despite his youth, Zouma has now explained Mourinho did not hold back in his criticism after a poor performance, per RMC Sport (h/t Goal's Peter Lynch):
"I cannot remember which match we were playing, we were losing 3-1, away from home.
"The following day, he [Mourinho] catches up with me, he takes me to his office, and he asks me if I am ok. I said yes, he asked me if I was sure.
"I said yes again, he replied ‘Because you were rubbish this weekend.’ Like that, direct. It shocked me, but it made me want to immediately respond on the pitch.
"I remember that it hurt me, that it affected me. But I really wanted to show him that I could react."
Zouma played 15 Premier League games in his debut season at Chelsea when the Blues won the Premier League.
He then made 23 appearances in 2015-16 in the English top flight when Mourinho was sacked after a dismal start to the season.
But under Frank Lampard in 2019-20, he has reestablished his spot in the Chelsea first team, playing in 20 of their 25 games this term.
The Blues have been on their Premier League winter break since February 1, but they are back in action on Monday when they face Manchester United at home.
It could be a crucial match in the battle for the top four:
Chelsea have won just one of their last five league games and have been dragged into a battle for the final UEFA Champions League spot as a result.
If they lose to the Red Devils, they could drop out of the top four altogether, and it will be a battle to get back in.
If they beat United, though, the Blues will not only hold onto fourth place, they will deal a big blow to one of the other competitors and give themselves a big psychological boost after a poor run.