Michal Helik then struck the winner in the 59th minute, blasting a close-range volley into the roof of the net.
Ismael said: "Congratulations to the guys for the performance and the mentality on the pitch.
"It was a tough game – it was exactly as we expected against Millwall. We were prepared for the direct game today. That's why we put a lot of bodies and physicality in the starting XI today, to compete at that level.
"I think we started very well and we scored quickly. To concede the goal was really poor. There was a concentration failure.
"After that it was a fight and a 50/50 situation on the game. In the second half we made a tactical change to have more pace behind.
"Today was a great team effort. To show a desire to keep moving and stay on the winning way.
"For sure, it was another game and it was another fight but we did it and we won and it's a great feeling tonight."
Millwall's best chance to draw level came in the 73rd minute when Bennett found himself with just the keeper to beat but he fired over.
Lions manager Gary Rowett said: "I thought it was a very close game. I thought we were the better side in the first half and they were probably the better side in the second half.
"We started poorly and two moments in the game undo us. It's two set-pieces – the second one a second phase – and for both goals we don't win the first ball and then we don't react to the second ball.
"The first goal is offside. I'm not going to massively complain about it but it's a clear offside and I think the linesman should certainly be able to see that.
"After the goal we settled well. They are really direct. They're probably the most direct side that I've seen in the Championship. They're good at it.
"We had so many opportunities to just put a ball with a little bit of height into an area for someone to run on to.
"There was nothing in the game. It was two set-pieces and we had our one big chance in the second half.
"It's the Championship and you don't always get what you deserve. We didn't play with enough quality and we didn't defend set-pieces."