After his side produced a superb comeback to draw 2-2 at Juventus in their Champions League last-16 first leg, Pochettino recounted the day he met Mason as a frustrated academy player that went on to make 53 Premier League appearances under the Argentinian.
"I remember very well how we found him the first day; sitting in the gym, head down and so sad," Pochettino said. "I asked Jesus [Perez] 'who is this guy?' And he said 'Ryan Mason, who in the last five seasons has always been on loan and never played because he suffered a lot of injuries'.
"It was difficult for him in the beginning because he struggled to cope with the training sessions, because it was very tough. But then we travelled to the USA and I met him in the airport and, during 30 minutes, we shared, and I said after to Jesus 'wow, I love Ryan'. I didn't know if he played well or not but I loved him like a man.
"Then, in the first game we played against Seattle, he understood everything. After only a few tactical training sessions he was quick and he understood everything - the movement and the timing and the concept - that maybe for another player it takes a whole season, and I said 'we have in front of us a very good player'.
"Always he is and will be a special player for me because he represent a little bit this change in all the processes when we arrived at Tottenham.
"Sure he was a very successful player, and sure he will be a very successful person in football, and everything that he is going to do. It is very sad news but it opens up a massive future (for him). He is 26 but he is an amazing person and has an amazing football brain.
Of course the door is open to help him; myself, the coaching staff and the club, because we love him and all his family. In the last few days he was at the training ground. He was talking a lot with us, the coaching staff and (academy boss) John McDermott.
"Don't worry Ryan because you are going to be a successful person in football outside of the pitch, no doubt about that."