When the Rovers teamsheet was published it caught out most people, not least Millwall boss Neil Harris.

A three man defence was the outcome, with the return of Tosin Adarabioyo, and a first league start for John Buckley in midfield.

Rovers, under Tony Mowbray, are no strangers to particular formation but it’s a system they have shelved of late.

The international break has given them the opportunity to work on it on the Brockhall training pitches, but that is a far cry from the heat of Championship battle.

Mowbray prefers to focus on principles of play than formations, believing they can be utilised whatever the system.

He feels his side can be versatile in the way they go about things, and certainly having more than one way of playing can be beneficial.

Harris conceded post-match that it certainly took his side by surprise, and changing twice more during the course of the 90 minutes certainly helped Rovers take charge of the second half and in the end run out comfortable, and deserved, victors.

When done at the right times, and for the right reasons, it can be a game-changer.

However, if Rovers are, as their manager wants, to become a versatile side they must do it to not become one-dimensional, not just for change’s sake.

Mowbray went as far to say he ‘didn’t enjoy’ the 90 minutes. He would have loved the result, and another clean sheet, but in a strive for a perfect performance, Rovers did fall short.

They led at the break courtesy of a Derrick Williams thunderbolt in the 18th minute, striding forward from his position as the left-sided centre back to arrow an effort in to the bottom corner.

They also missed the clearest opening of the half, five minutes before the break, when Elliott Bennett snatched at his chance having been played in by Bradley Dack.

Inbetween, much of their possession came with passes exchanged among the back three, and a struggle for fluency saw Millwall get a foothold in the game, albeit their opportunities restricted to long-range efforts.

Then came the second switch, Dack going in as a false No.9 with Sam Gallagher sent on to flank him to one side, and Adam Armstrong moving to the left.

It was a bold move in that it would open up the game, taking a man out of what was a congested central midfield area. What it did do was pin Millwall back with Stewart Downing in particular relishing the opportunity to have runners ahead of him.

Chances started to come.

Downing drew the first of several smart stops from goalkeeper Bartosz Bialkowski with a low 25-yard drive before Armstrong should have given the ‘keeper no chance when he danced his way in to the six yard box, only to see a left foot shot kept out by the Pole.

Dack couldn’t get the required contact to turn home a Cunningham cross before the third, and final, change of formation arrived.

Joe Rothwell, a man whose game is well suited to when space is opening up, replaced Tosin Adarabioyo as Rovers returned to their more familiar 4-2-3-1.

Rothwell was quickly in to the action, before the second goal which Rovers, and Dack, had threatened arrived.

Darragh Lenihan, who had moments before thrown himself in front of a Jed Wallace shot, fizzed a ball across the six yard box with Dack able to steer home at the far post.

By this point Millwall had thrown caution to the wind, finishing the game with almost a five-man frontline.

That only played in to Rovers’ hand as when possession changed hands, they were able to spring in to life.

That brought them two more excellent openings before the final whistle. Rothwell steamed up on the outside of Downing and after collecting his pass, steered an effort towards the bottom corner, only to be denied by a fine one-handed stop by Bialkowski.

As Rovers dealt with an aerial bombardment to keep the back door shut, with Christian Walton confined to claiming balls in to the box, they went close to a third in injury time, only for Armstrong to thump a shot straight at Bialkowski.

Three points, a fourth clean sheet in five games, and in to the top half, it was a job well done for Rovers.

It might not have been as fluent as the manager would have liked, but if Rovers are to have top six aspirations this season then making games like this as routine as possible will be key