NEIL Harris believes St Andrew's will be hostile on Saturday – but not intimidating for Millwall players.
The Lions travel to Birmingham looking for a third successive away league win and to stretch their unbeaten Championship run to six games, after last Friday's 1-1 draw at home to Cardiff.
Birmingham were bottom of the table on Boxing Day, but Steve Cotterill, who took over from Harry Redknapp in September, has guided them out of the drop zone.
Birmingham lost 2-0 at city rivals Aston Villa last Sunday, but Harris is impressed with the job Cotterill is doing.
"They'll take that defeat with disappointment, it's a derby and they are arch enemies," Harris said. "Steve has done a great job since he's gone in there. They've got some fantastic talent, great players.
"Steve has put his stamp on it and they've got a settled team and formation. They are really hard to play against. It's going to be a tough game.
"We go there full of confidence on the back of two away wins in a row. It's going to be a better team than we faced at The Den three months ago.
"It's not an intimidating place as a Millwall player. We'll have a great following up there. It's a hostile atmosphere, a great atmosphere to play in. It will bring out the best in both teams, I'd imagine.
"We have to make sure we battled like we did Friday night, win first balls, second balls. They're a really strong side and I've been impressed with them recently. We look forward to it."
Lions midfielder Ryan Tunnicliffe scored his only goal of the season in the 2-0 win over Birmingham at The Den in October.
He says the squad will have their homework done on this weekend's opponents.
"As we always do every week we'll watch some clips of them and plan accordingly," Tunnicliffe stressed. "The game at The Den is still quite fresh in the memory because it was on the telly and I scored as well.
"I think they are a different team, they have started to pick up results and it's going to be another tough one.
"But with the confidence we've got at the moment we'll be going into it fully expecting to win the game."
Image: Millwall FC