Goals from Derrick Williams and Bradley Dack condemned Millwall to a 2-0 Sky Bet Championship loss at Blackburn Rovers on Saturday afternoon.
Tony Mowbray's men struck in either half to inflict a second defeat of the season on The Lions.
Millwall boss Neil Harris handed first League starts to Jayson Molumby and Jon Dadi Bodvarsson, whilst both Tom Bradshaw and Matt Smith dropped to the bench.
Ryan Leonard had the first effort of the afternoon with just two minutes played, but after carving out an opportunity for a shot from distance, Christian Walton gathered comfortably. Bodvarsson then had time to cross, but Elliott Bennett was just able to stop former Rover Connor Mahoney from getting an attempt in on goal.
The home side began to gain a foothold from there, however, and tightened their grip on possession of the football, but could only muster a long-range effort from Adam Armstrong - one Bartosz Bialkowski claimed with ease.
A neat passing move nearly secured the opening goal with 16 minutes played, but after the ball was laid off into the path of Jed Wallace, his first-time shot went well wide. Two minutes later, though, the scoring was opened as Derrick Williams' sweetly-struck shot flew into the far corner, giving Bialkowski no chance.
Leonard then again tried his luck from distance, with this one whistling past the post, before a deep corner-kick saw the ball loop in the air from Jake Cooper's header - Walton rose to grasp, however. Mahlon Romeo then twisted and turned in an attempt to equalise, but his low drive was saved.
Seven minutes from the break, Mahoney's in-swinging corner looked to have found Cooper at the back post, but the towering centre-half was just unable to reach the ball for a free header which would've seen the scores levelled. Just two minutes later Rovers could have doubled their lead, but Bennett dragged his effort well wide.
There were half chances at either end in the opening stages of the second-half - Bodvarsson nearly having Millwall's - but the score remained the same, with the next effort coming on 53 minutes as Bialkowski palmed away Stewart Downing's shot.
Armstrong then danced through Millwall's slack defence and looked set to score, but Bialkowski pulled off a great save to keep The Lions in the game. That nearly paid instant dividends, but Mahoney's cross at the other end was cut out inches before reaching the onrushing Bodvarsson.
Alex Pearce blocked substitute Joe Rothwell's shot with 20 minutes remaining, before Leonard again had an attempt, this time from the edge of the penalty area, but the effort fizzed over the crossbar.
With 15 minutes remaining Rovers doubled their lead, as a cross made its way across the six-yard box before being steered home by Dack.
A double change saw Bradshaw and Shane Ferguson make their way on to the field in place of Murray Wallace and Leonard, but the next chance went the way of the home side - Bialkowski - again - however, kept the score down with a fantastic save from Rothwell.
Try as they might, any potential consolation goal for The Lions was not to come, as they slipped to a second loss of the campaign.
Blackburn Rovers: Walton, D. Williams, Johnson, Cunningham, Armstrong, Downing (Travis 86'), Dack, Adarabioyo (Rothwell 63'), Lenihan, Bennett, Buckley (Gallagher 46'). Subs not used: Leutwiler, Nyambe, Graham, Travis, Evans.
Scorer: D. Williams 18', Dack 75'
Millwall: Bialkowski, M. Wallace (Ferguson 76'), Cooper, J. Wallace, Thompson, Romeo, Pearce, Molumby, Leonard (Bradshaw 76'), Mahoney (Smith 59'), Bodvarsson. Subs not used: Steele, Hutchinson, S. Williams, O'Brien.
Referee: Dean Whitestone
Attendance: 11,873 (580)