Neil Harris says Millwall were left surprised by Rovers’ change in formation in the defeat at Ewood Park.

Tony Mowbray moved to a back three for the visit of the Lions who had been beaten just once in their opening six games.

But goals from Derrick Williams and Bradley Dack saw Rovers to victory, with Harris conceding Rovers were the better side in the second half.

However, Harris was left disappointed that referee Dean Whitestone failed to award his side a penalty for what he felt was a foul on Jake Cooper from a second half corner with the score at 1-0.

“First half we were the better team, we controlled a lot of the possession,” Harris said.

“Second half Blackburn were better than us. When teams are better than you, you need to stay in the game, stay in the game. When the game’s 1-0 you’ve always got a chance with attacking players on the pitch, even if you have to ride your luck.

“But we give a really poor second goal away. Players have to do what instructions are given to them, not what they want to do.

“I was a little bit surprised by Blackburn’s formation, changing to a five at the back. They made it difficult for us in the final third to create the chances.

“You’d have to ask Tony how many times he’s played a back five at this club, it’s probably very rare. I’ve never known him to do it here, so he’s caught us by surprise, definitely. But I thought we adjusted really well."

Six minutes before Dack scored Rovers’ second goal, Harris his side should have been awarded a penalty for holding in the box.

He told Southwark News: “In the 68th minute, and I’ve seen it back from two different angles, we’ve got a stonewall penalty from a set-piece when the game’s at 1-0. The referee talks to Sam Gallagher on marking Jake Cooper, Jake gets a run and the player’s on the wrong side and manhandles him to the ground. It was almost a rugby tackle.

“The referee is seven yards away and doesn’t give it. For me he bottles it. He has to give that decision, what’s the point of talking to the player? What game are we playing here?

“We’re a team that’s physical and aggressive, we get the ball forward. We play to win set-plays. When you win them you need some help.”

Millwall responded well to going behind to Williams’ 25-yard strike and dominated the latter stages of the first half but struggled to create any clear-cut chances.

“I’m disappointed with the goal we conceded. I was very disappointed to be behind at half-time, I thought it was unjust, we didn’t deserve to be behind.

“I thought we started well and when you start well you want to get in front. The home team come back into it and you have to get a foothold in the game again. The last 20 minutes of the first half we were the better team without clear-cut chances.

“That’s the difference between teams at this level: Their centre-half puts the ball in the bottom corner from 25 yards; We have three shots from in and around the penalty area and don’t score. That’s not knocking my players, that’s just the difference, that’s the fine lines. In the final third they created four or five good opportunities on the counter-attack, we counter-attack and we don’t get the opportunities.

“I thought we were a little bit scruffy around the penalty area and ultimately that’s what costs money in this division. We have to keep working and keep trying to improve.”