Millwall defender Sid Nelson and striker Aiden O'Brien have signed new contracts with the club following their relegation to League One.
Nelson has signed a three-year contract while O'Brien has agreed a two-year deal, with an option for a further 12 months at The Den.
Centre-back Nelson, 19, made his debut for the Lions in December and featured a total of 15 times last season.
O'Brien, 21, scored two goals in 20 appearances for Neil Harris's side.
"Sid and Aiden have made fantastic progress over the last 12 months and this is their reward," Millwall chief executive Andy Ambler told the club website.
"Neil believes that the club's current crop of youngsters can play a big part in both the short and long-term future.
"Retaining the services of these two talented players is an important step."