Sean O'Brien found the net twice as Millwall's Under 23s defeated Royston Town 2-1 in a pre-season friendly on Friday night.
The attacker scored in the 23rd and 59th minutes, either side of a Royston goal, to give Kevin Nugent's side the victory.
New signing Seb Drozd played 90 minutes at Garden Walk.
Millwall's Under 23s begin their 2021/22 Professional Development League campaign at home to Crewe Alexandra on Tuesday 17th August.
Millwall: Gillmore (Wright 46'), Walker (Trialist C 60'), Penney, Trialist A (Trialist B 46'), Topalloj, Tiensia, Allen, Moss, Davis, O'Brien, Drozd.