The young midfielder is a candidate to fill the void left by new PSG signing Gini Wijnaldum.
But Robertson told the club's website: "Curt is coming of age. I thought last season at times he was outstanding but it's now about the consistency, it's always about that and doing that on a week-to-week basis. Curt is a great kid, I've got a lot of time for him, I try to take him under my wing – probably more so than anyone.
"He always bounces things off me and I hope this is a big season for him because, like I said, he's a fantastic player and he's a fantastic person. I just hope that he can find that consistency, keep that hunger that he's got and he'll only get better.
"You still need to let them improve but I think hopefully there's a big season ahead for all of them."
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