Millwall 1 Sheffield Wednesday - Matt Smith header sees Owls fall to first defeat under caretaker manager Lee Bullen
Sheffield Wednesday slipped to their first league defeat of the season, losing 1-0 to 10-man Millwall.
Matt Smith's 37th minute header from Connor Mahoney's corner proved decisive as the Lions registered only their third home league victory in 2019.
Millwall played all of the second half with 10 men after Jed Wallace was sent off for a late challenge on Kieran Lee.
Wednesday piled on the pressure after the break, creating a number of opportunities but a combination of poor finishing and inspired goalkeeping from Bartosz Bialkowski kept them at bay. They had over 20 attempts at goal, including nine on target.
But Millwall, led brilliantly by captain Alex Pearce and Jake Cooper, produced a superb backs-to-the-wall performance to take the spoils.
There were plenty of wayward passes from both sides in the early skirmishes. Millwall tried playing to their strengths by knocking the ball long to giant striker Matt Smith but Wednesday's defence initially stood up well to their direct style of play.
Adam Reach, fielded in central midfield for the second match running, forced Bartosz Bialkowski into a good save in the 15th minute after good play by Kadeem Harris but the offside flag had already been raised.
After a quiet opening, the Owls enjoyed a good spell of pressure and Liam Palmer saw a fierce strike turned behind by Bialkowski.
Reach tried his luck from 35 yards out with a stunning half volley but his looping left foot drive flew on to the top of the net as Bullen's men continued to press for an opener.
Julian Börner came to the visitors rescue in the 31st minute when he hooked away Jed Wallace's dangerous cross from the right in a rare opening for the Lions, who finished fourth-from-bottom in the Championship last season.
Bullen told his team in the build-up to the trip to The Den that Millwall would be a major threat from set pieces.
But his warning fell on deaf ears as the hosts opened the scoring in the 37th minute, Smith rising highest to head in Connor Mahoney's corner after Keiren Westwood was caught in no man's land.
There was a strong response from the Owls, with Jacob Murphy bending a right doot drive narrowly wide after Dominic Iorfa, preferred to Moses Odubajo at right-back, won the ball back deep inside Millwall's half.
Two minutes before half-time, the hosts were reduced to 10 men after Jed Wallace's late, clumsy challenge on Kieran Lee. Referee Gavin Ward sent the winger off after consulting with his linesman but the decision angered the home faithful.
Wednesday finished the half strongly, with the lively Kadeem Harris cutting in from the left before unleashing a rasping shot that Bialkowski was equal to.
Caretaker boss Lee Bullen made an attacking change at the interval, throwing on Barry Bannan for Iorfa. Sam Hutchinson moved to right-back following Bannan's introduction.It did not take Bannan long to make his presence felt as he sprayed the ball out wide to Harris. He surged into the box and fed Murphy, whose shot was well saved by Bialkowski.
Bannan then clipped a lovely ball into Fletcher but his strike lacked power and direction as Bialkowski held on.
Millwall were compact and disciplined and threatened to bag a second through Aiden O'Brien. His ferocious effort from near the edge of the penalty area was acrobatically tipped behind by Westwood.
Bullen kept tinkering with his team in search of an equaliser. Massimo Luongo and Jordan Rhodes replaced Palmer and Lee respectively. His tactical alterations meant Reach switched to left-back and Rhodes partnered Fletcher in attack.
Harris was a great outlet throughout on the left and he squared the ball to the influential Bannan only for Bialkowski to again come to Millwall's aid.
It took a strong, inch-perfect tackle from Jake Cooper to prevent Fletcher from turning in Hutchinson's low cross as the hosts continued to put their bodes on the line to keep Wednesday at bay.
It just was not the Owls' day in front of goal as Bialkowski spread himself well to thwart Hutchinson following another promising attack.
Millwall: Bialkowski; Romeo, Cooper, Pearce, M Wallace; J Wallace, Williams, Thompson, Mahoney (Leonard 74); O'Brien (Ferguson 83), Smith (Bradshaw 52). Substitutes: Steele, Hutchinson, Bodvarsson, Skalak.
Owls: Westwood; Iorfa (Bannan HT), Lees, Borner, Palmer (Luongo 59); Hutchinson, Lee (Rhodes 65), Reach; Murphy, Harris, Fletcher. Substitutes: Nuhiu, Fox, Odubajo, Dawson.
Referee: Gavin Ward (Surrey)