He revealed that playing and training alongside the likes of Kolo Toure (now with Manchester City), William Gallas (Tottenham) and Sol Campbell (Newcastle United) has given him plenty of confidence to mix it with the best in Scotland.
"Then the likes of Sol Campbell came in. I played with him in a reserve game and he talked to me a lot which was fantastic.
"You can only improve your game by being around those sort of players and you just take a lot of positives from them."
Bartley and his 'Gers teammates are preparing for Thursday's Europa League Round of 16 first leg against PSV Eindhoven in Holland.