Millwall F.C 4 -0 Bristol Rovers
Attendance: 9645 (1,018 away)
Daniel Leadbitter was shown an early red card as Rovers are defeated by goals from Aiden O'Brien, Shaun Williams, Lee Gregory and Harry Smith at the Den.
Heading into the match, Rovers made six changes from the side that faced Portsmouth in the Checkatrade Trophy on Tuesday evening.
Tom Lockyer returned to captain the side, with Matty Taylor and Ellis Harrison providing the attacking options at the Den.
In midfield, Stuart Sinclair and Chris Lines returned to the starting line-up alongside Charlie Colkett and Hiram Boateng, with Lee Brown returning to the side at left-back.
Inside the opening minutes, the hosts squandered the first opportunity of the game, when striker Lee Gregory received the ball in space inside the Rovers area but opted to flick an effort towards goal with the outside of his boot which was watched over the crossbar by Kelle Roos.
Rovers were quick to create chances of their own and looked a threat from set-pieces. Ellis Harrison came close with a glancing header from a corner, which was followed by Peter Hartley losing his marker from a corner from the left by Chris Lines and the centre-back sent a powerful header goalwards that was stopped by a stray boot on the line by Ben Thompson.
Matty Taylor created a chance of his own early on, with the forward holding up the ball well before hitting a bending shot from twenty-five yards out that narrowly flashed past the post.
Rovers were reduced to ten men in the 14th minute when a stabbed ball forward bounced into the path of Aiden O'Brien, who then collided with Daniel Leadbitter on the edge of the area. The referee produced a straight red card for the right-back, giving a free-kick on the very edge of the Rovers area, which when the resulting set-piece was taken, it was blocked by the defiant Rovers wall.
Goalkeeper Kelle Roos was called into action twice in quick succession shortly after, as the hosts looked to make their man advantage count, with the shot-stopper diving to his left to deny Harry Smith from a header and then moments later pushing a threatening free-kick past the post.
To compensate for the red card, Rovers introduced Mark McChrystal at the expense of Charlie Colkett, a move that saw captain Tom Lockyer fill in at right back.
After a dramatic opening twenty minutes, it was Millwall who took the lead when a Lee Gregory shot from inside the area was blocked by Roos, but striker Aiden O'Brien was on hand to follow up and poke the ball home from close-range to open the scoring.
Rovers had to be patient in defence, with the home side energised by the goal, but after a spell of calm possession on the edge of their own area, midfielder Hiram Boateng was able to drive into the Millwall half and after avoiding a series of challenges, Boateng directed a well-struck shot towards goal that rose over the crossbar.
Heading into the break, Rovers were able to hold possession well and just prior to half-time a well-worked series of exchanges in midfield led to Lee Brown breaking down the left-wing and aiming an inviting delivery into the area that found Matty Taylor, but the forward couldn't direct his header past Millwall 'keeper Joran Archer.
After the half-time break, Rovers continued in the same fashion as they ended the first-half, with a driven forward run with the ball by Hiram Boateng allowing the midfielder the opportunity to break into the area, but after doing well to find space to shoot on goal, his effort lacked the power to trouble the Archer in the Millwall goal.
Millwall had a chance of their own as the game went past the hour mark, when a well-directed delivery into the Rovers area was met by Shaun Williams who attempted a diving header from six-yards out that bounced wide of the target.
Williams was involved in the thick of the action moments later, receiving the ball at a comfortable height inside the box and firing a left-footed volley that found the target and powered past Kelle Roos to double the lead for the hosts.
Rovers introduced Cristian Montano to add some pace out wide, but it was Millwall who found the net again, with Lee Gregory controlling a bouncing ball on the edge of the area and striking a volley that hit the back of the net at some pace, giving 'keeper Kelle Roos little chance to make a save.
Matty Taylor was replaced by Jermaine Easter inside the closing fifteen minutes, but Rovers couldn't carve out any clear chances on goal.
With Rovers making their full allocation of substitutes and the game nearing its conclusion, Kelle Roos again produced a fine reaction save, leaping down low to his right to tip a Harry Smith header away from goal.
The hosts added their fourth goal of the afternoon when Harry Smith was on hand to tap home from close-range after Millwall had hit Rovers on the counter attack down the left-wing.
Rovers are back in action on Tuesday night at the Mem, as they host Crawley Town in an Emirates FA Cup First Round replay.
Rovers: Kelle Roos, Tom Lockyer (C), Peter Hartley, Lee Brown, Stuart Sinclair, Chris Lines, Hiram Boateng (64' Cristian Montano), Charlie Colkett (21' Mark McChrystal), Matty Taylor (72 Jermaine Easter), Ellis Harrison
Subs: Will Puddy (G), Ollie Clarke, Rory Gaffney, Luke James
Millwall F.C: Joran Archer (G), Joe Martin, Tony Craig (C), Shaun Williams (86' Shaun Cummings), Ben Thompson (71' Calum Butcher), Lee Gregory, Fred Onyedinma, Mahlon Romeo, Byron Webster, Aiden O'Brien (61' David Worrall), Harry Smith
Subs: Tony King (G), Gregg Wylde, Alfie Pavey, Paul Rooney