Derrick Williams and Bradley Dack scored the goals as Blackburn secured victory over Millwall at Ewood Park.
Williams drove the ball home from 20 yards after there had been little to choose between the sides in the opening exchanges.
The Lions struggled to carve out chances and most of their first-half efforts were from outside the box.
Adam Armstrong almost made it two after the break, only to be denied by Bartosz Bialkowski’s reaction save, but the Millwall keeper could do nothing as Dack slid home Darragh Lenihan’s square ball to seal the points.
Both managers made two changes for their first game after the international break, with Tosin Adarabioyo and John Buckley in for Rovers, and Jayson Molumby and Jon Dadi Bodvarsson making their first Championship starts for Millwall.
Bodvarsson provided the pass for an early shot by Jed Wallace, but it was off target and the visitors fell behind when Williams found the bottom corner after receiving the ball from Greg Cunningham.
Lions boss Neil Harris sent on Matt Smith in the second half to provide a more physical presence up front and Ryan Leonard was only just too high from Bodvarsson’s lay-off.
Millwall’s hopes were ended when Dack found the net for the third time this season and, although Ben Thompson tested home keeper Christian Walton after beating two tackles, they could not find a consolation goal and are now without a win in four league games.