Millwall's second string slipped to a 2-1 friendly defeat at Tooting & Mitcham on Tuesday evening.
A strong Lions side had keeper Preston Edwards to thanks for pulling off three top-notch saves in the opening 10 minutes as Tooting came flying out of the traps.
But there was nothing Edwards could do to keep out Joe Vines' 25th-minute bullet header as the home side edged into a 1-0 lead.
Vines' brother Paul doubled Tooting's lead five minutes later with a virtual carbon-copy headed goal.
Millwall reduced the deficit just past the hour mark when Marcus Bignot was flattened in the penalty area. The right-back picked himself up, dusted himself down and thumped home the resulting spot-kick.
Ahmet Brkovic then curled a free-kick tantalisingly over before Gary Bowes contrived to sidefoot past the post with just the keeper to beat.
Hard as they tried, that late leveller proved elusive for The Lions and Tooting held on for victory.

Millwall: Edwards, Bignot, O'Connor, Ebsworth, Barron, Bowes (Tevfik), Dunne, Spiller, Brkovic, Forbes, Keen (Marquis). Subs not used: Walker, Read, Mason.