Millwall were predictably a threat at set pieces and the giant Jake Cooper proved a big problem, the centre-back providing a headed assist from a free-kick for Japhet Tanganga to net the only goal of the game five minutes before the break.
Leeds huffed and puffed and joy turned to dismay midway through the second half when Joel Piroe thought he had drawn his side level, only to be greeted by an offside flag. Whites boss Daniel Farke then threw on an array of forwards but only the frame of the goal denied Millwall a second goal from a set piece as Mateo Joseph’s attempts to clear a Cooper header bounced back off the post.
Leeds needed to win to climb back into the division's automatic promotion places after Tuesday night's victory for Sheffield United at Bristol City but the Whites now remain third, two points behind the Blades and now four pints behind leaders Sunderland.
Victory for Millwall also sent the upwardly mobile Lions into fifth and now just four points behind Leeds who are only three points ahead of fourth-placed Burnley who also have a game in hand.
Graham Smyth, the YEP’s chief football writer, hands out the scores from a night to forget at The Den.