The pair played together at Southampton.
Cork told WalesOnline: "I obviously know Luke very well from playing with him last year and he had an excellent season for us. He always stood out for his talent and potential. He was a good lad and always a major threat down the left-hand side, while also being excellent defensively, he was always difficult to get around because he was so quick and strong. It was obvious he was always going to go on in his career.
"He is still only 19 and he has got a great future ahead of him and although he had a difficult start there he is starting to settle.
"It took him a bit of a time; £30million is a lot of money to move for and there were a few things that did not do him any favours early on.
"And when you are that young those things can get in your head no matter how old or experienced you are. But he has come good, he has dealt with the pressure and I am sure United will see the best of him."
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