Defender Mahlon Romeo has signed a new "long-term contract" with Championship side Millwall.
The 24-year-old has made 172 appearances for the Lions since his move from Gillingham in 2015.
Antigua and Barbuda full-back Romeo has remained a regular under Gary Rowett, having established himself when former boss Neil Harris was in charge.
He was a member of the 2016-17 League One play-off final-winning squad and has played 37 games this season.
Meanwhile, midfielder Billy Mitchell, 18, has also signed a new deal with the club.
The teenager, a Millwall fan, has played six first-team games since joining as a schoolboy.