Fred Onyedinma has put pen-to-paper on a new long-term contract at Millwall.
The midfielder, who graduated through the club's Academy, has signed a three-year deal, committing his future to The Lions until the summer of 2020.
Since making his first team debut in 2014 as a 17-year-old, Onyedinma has gone on to feature 106 times for Millwall, including as a substitute in May's League One Play-Off Final win over Bradford City at Wembley Stadium.
He told millwallfc.co.uk: "I love playing for this club and am delighted to have signed a new deal here.
"The manager has always been great with me, right back to when he gave me my debut against Southend, and I'm looking forward to improving under him further in the coming years.
"Now my focus is on continuing to work hard during pre-season so I can play as big a role as possible in the Championship for Millwall."
Neil Harris added: "Naturally I'm very pleased to have concluded this deal.
"It's no secret that it has taken time, which for various reasons these things can do. At this time of year, in June and July, people are away on their holidays so tying up deals can take time.
"I've always been relaxed about it because Fred has reiterated throughout how happy he is at Millwall and how keen he is to stay.
"He is a boy with huge potential. Fred has improved immensely over the last 12 months and has a bright future in football. It's important to remember he is still only 20.
"This is another piece of the jigsaw complete as we prepare for the new season."