The Scot was tipped for big things from a young age and finally got his move to a top-four club in the summer when he joined Liverpool from Hull.
Whilst he was slowly introduced to life at Anfield, Robertson has shone since, making the left-back berth his own, something which Mason has not been surprised to see.
"I see the potential. He excelled and stood out in a team that were in a relegation battle last year," he told 'Sky Sports News'.
"To do that as a defender is very difficult. He has gone to Liverpool, had to wait for his opportunities and taken his time.
"Klopp seems to be the kind of manager that has tried to get him used to the training regime and how Liverpool play but he has come and fitted in.
"This second half of the season he has been exceptional."