Wednesday slipped to their maiden defeat of the new season as a Matt Smith header was enough to earn three points for ten-man Millwall.
Smith struck in the first half before Jed Wallace was dismissed for a lunge on Kieran Lee. And that meant an uphill battle for the hosts in the second period, a challenge they were equal too as Neil Harris’ side held firm despite sustained Owls pressure.
Try as they might, Wednesday could not find a way through the resolute Millwall defence, which proved the foundation for victory.
The first 20 minutes passed without incident or any real quality, with possession shared and chances at a premium.
Indeed, it was midway through the opening period when the first shot on goal arrived as Liam Palmer warmed the hands of Bartosz Bialkowski from the angle of the penalty area.
The Owls grew into the game and asked more of the Lions, whose main threat was from set pieces, with the tricky Connor Mahoney the architect.
But on 27 minutes it was Wednesday who were a whisker away from taking the lead when Adam Reach swivelled 40 yards out and executed a delicious volley that brushed the top of the net with Bialkowski peddling backwards.
And that was perhaps a turning point as Millwall advanced and broke the deadlock ten minutes later.
Mahoney swung a hanging corner to the back stick, where Smith climbed high to nod home.
The Owls replied with Jacob Murphy going close with the outside of the foot from range before Millwall suffered a blow three minutes before the break.
Wallace was late with a challenge on Lee right under the nose of the referee’s assistant and after a brief consultation the verdict was red.
The interval gave Lee Bullen the opportunity to shuffle his pack and Barry Bannan was introduced for the restart.
The midfielder’s impact was immediate, pulling the strings in trademark style from the off.
Bannan fed the lively Kadeem Harris on 47 minutes with a sweeping ball, the wideman crossed for Murphy and only the alertness of the diving Bialkowski prevented a leveller.
The Owls may have had the numerical advantage but Millwall posed the odd threat on the counter, as evidenced by a stinging Aiden O’Brien drive that Keiren Westwood tipped over.
Play soon reverted to type and Wednesday were squarely in the driving seat – Bannan forced a fine save from Bialkowski.
Steven Fletcher was denied at the back stick by some desperate defending and substitute Jordan Rhodes glanced just wide from the resulting corner as the clock ticked down.
Bialkowski dropped on a Sam Hutchinson effort and there was little relief from the one-way traffic for the beleaguered Lions.
But against the odds and under the cosh, they held out for the hardest fought of three points.
Wednesday: Westwood, Iorfa (Bannan 46), Lees, Borner, Palmer (Luongo 59), Harris, Hutchinson, Lee (Rhodes 65), Reach, Murphy, Fletcher