Jack Stephens has signed a new five-year deal at Southampton, the Premier League club have announced.The 23-year-old defender impressed after nailing down a first-team place following Virgil van Dijk's season-ending injury in January. England Under-21 international Stephens, who has been with Southampton since he was 17, is highly rated by the club, with executive director Les Reed saying: "Our philosophy at Southampton is to turn potential into excellence, and Jack is somebody who very much embodies this. "His progression, and the level of his performances, was one of the real highlights of last season, and we have been delighted with his development ever since he joined the club. "We are extremely pleased to have strengthened our commitment with him, and we believe Jack can continue to improve here and play an important role in our first-team plans moving forward," he told www.southamptonfc.com. Stephens said: "I am absolutely delighted to extend my stay."It feels like home to me. I have really enjoyed my time here and am now looking forward to the next five years."It's a massive platform for me now because it just shows how much faith the club have put in me."