Sunderland's new arrival Adam Matthews has revealed that former Celtic teammate Virgil van Dijk is happy with the Scottish Champions.

Matthews claims that van Dijk, who is a defensive target for Sunderland, would find it hard to leave Celtic Park even if the right clubs came looking for him.

He told Sky Sports: "There has been talk of him moving for the last couple of season's but I think he is enjoying it up there like I did so I think it'll be a hard decision if the right people come in for him because he will have to think about it.

"He is a brilliant player for his age and for the way he plays you would think he is very experienced but he is only 23 or 24.

"He is still relatively young for a centre-back but he has a bit of everything - he has pace and he is good on the ball, so he will fit in to the Premier League very well if that ever happens. But I'm pretty sure he is still enjoying himself up at Celtic."