The Rangers midfielder has been one of the stand-outs at Ibrox recently.
Jack was signed from Aberdeen by Pedro Caixinha back in 2017 and has gone on to become an integral member of the Gers midfield.
Even through heavy recruitment the 27-year-old has managed to retain his position in the heart of Steven Gerrard's team and looks set to have another big season this term.
Miller was director of football at Pittodrie as Jack was emerging from the Dons' academy and has been recalling sharing his belief that the midfielder was set to become a star.
Delighted to see him flourish at Rangers, the former defender thinks he can go from strength to strength working under Steven Gerrard and Gary McAllister.
He also reckons that Jack will be motivated to win silverware with the Gers.
As quoted by The Scottish Sun, Miller said: "Everything he’s got so far he’s earned, and I hope there’s plenty more success ahead for him.
"To be truly regarded as a great then you are looking at trophies and caps.
"Ryan won’t be happy on that front, he’ll be driven to do better. It will be important to Jack to get more medals. I see him as a big part of Rangers’ pursuit of trophies."
Jack's start to the 2019/20 season suggests he may be capable of bringing his game on to new levels too.
His fight and drive in the midfield against Hibernian at the weekend must have been so pleasing for Rangers fans to see.
Miller's comments about winning caps stick out too.
Jack so far has been largely shunned by the Scottish national team set-up, making just two appearances to date. He hasn't been included in a squad since September of last year.
Competition is fierce, but if the player can continue his current run of form, then surely manager Steve Clarke will give him the nod for upcoming matches against Russia and Belgium?
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