JED Wallace scored his sixth goal of the season but it wasn't enough for Millwall who couldn't recover from conceding twice as they lost at Reading in Gary Rowett's second match in charge.
Millwall went behind in the 10th minute when Jordan Obita rifled a low first-time shot after Jake Cooper had headed away Liam Moore's long throw-in.
The Lions had an escape in the 20th minute when John Swift's free-kick from the left-edge of the box clipped the crossbar.
Bart Bialkowski brilliantly saved Matt Miazga's header but the Royals doubled their lead eight minutes before half-time when Sam Baldock received possession from Ovie Ejaria before advancing and firing into the top right corner from 25 yards.
Wallace halved the deficit when he went past three Reading defenders to fire low past Rafael Cabral in the 63rd minute.
Away day blues continue
It was March 2018 when the Lions last won away at 3pm on a Saturday, at Barnsley.
They went into this game 21st in the Championship's away form table, above only Stoke, Wigan and Barnsley.
They are a Jekyll and Hyde side and have been for some time. And it was true within this game, too.
Once again it was Wallace providing the attacking inspiration as his determination took him into the box. His finish was the product of a player high on confidence.
Millwall had the attacking momentum at that stage, and boss Rowett sent on Matt Smith and Conor Mahoney for Tom Bradshaw and Shaun Williams to give the side more set-piece firepower.
Smith hung around the back post but when he was picked out by Murray Wallace in injury-time he couldn't beat Cabral with a header.
Then Cooper, against his former club, nodded well over from another Mahoney delivery.
Bodvarsson almost gets wonder goal against his former club
Millwall shaded the possession stats in the first half but Reading had all the thrust and cut through the visiting defence too easily.
The Lions needed to hold the ball more effectively to allow more players to join attacks. But it was Reading who continued to dominate as the away side struggled to create a coherent attack and gave the ball away far too easily.
Wallace took it on himself to do the creating and the finishing.
Jon Dadi Bodvarsson almost made a spectacular impact but his overhead kick went inches wide of Cabral's goal in the 89th minute.
Lions set-piece shakiness
When Cooper headed away Moore's throw-in no Millwall player was quick enough to close down Obita, whose precise and powerful shot gave Bialkowski little chance as the ball fizzed by his left hand.
Earlier, Shaun Hutchinson cleared on the six-yard line and then Swift cracked an effort off the bar as the Royals looked a real threat from a variety of set-plays.
As the rain teemed down towards the end of the first half Royals goalkeeper Cabral's only real challenge had been to keep himself warm.
Bialkowski went from almost-villain to hero in the space of 30 seconds. The goalkeeper first spilled Baldock's shot before saving from George Puscas. The loose ball ran to Andy Yiadom whose shot was deflected over. From Swift's corner, Miazga was certain he'd scored when he flicked a header towards the far corner, but Bialkowski dived to his right to somehow tip the ball around the post.
The Lions kept giving away too much space in the centre of the pitch and when Baldock was given an invitation to shoot the striker emphatically accepted it.
The hosts had eight shots on goal in the first half, five on target to none for the visitors, who had a steep hill to climb after the break. It was something they just couldn't manage to do.
Rowett named the same team and bench as last week.
Millwall: 4-4-1-1: Bialkowski; Romeo, Hutchinson, Cooper, M Wallace; J Wallace, Molumby, Williams (Mahoney, 78), Ferguson (Bodvarsson, 46); Thompson; Bradshaw (Smith, 78).
Subs: Steele, McCarthy, Pearce, Mahoney, O'Brien.
Image: Millwall FC