Central Coast youngster Marc Warren will leave the A-League club this week after signing a two-year deal with English Championship side Sheffield United.The 19-year-old has not yet made his A-League debut, but Sheffield were suitably impressed with the talented left-back during a two week trial recently.Mariners coach Graham Arnold has no doubt Warren will be able to transition successfully into the English competition."Waz is a fantastic kid," he said."He always puts 110 per cent in at training and loves his football. He's great to have around the squad and I'm sure his football talent will only improve being around such a professional setup as Sheffield's."Warren sees the Sheffield deal as a positive step for his career."It's an amazing opportunity," he said."I learned so much just during the two weeks I was there and I can't wait for this experience."The two clubs share a close relationship, having seen the likes of Trent Sainsbury and Andrew Redmayne trial with the English club."It's a fantastic opportunity for Marc and I know he is really excited," Mariners chairman Peter Turnbull said."I'm delighted that our relationship (with Sheffield) continues to strengthen."