Millwall boss Neil Harris was “surprised” by Cardiff’s January transfer business.

The Bluebirds paid around £6m for Bolton striker Gary Madine and loaned in highly-rated Liverpool midfielder Marko Grujic.

Harris, whose Millwall side host fourth-placed Cardiff tomorrow, said: “They had that sticky little spell around Christmas time that may have forced their hand to do some more business.

“They spent almost £6m on a striker that has had purple patches.

“It was a little bit surprising but totally unexpected? No, because of the market we live in and foreign ownerships show they’re willing to drop the hat and go and spend money at any cost.

“The size and quality of their squad, it’s there for all to see. They’ve got themselves in the top four all season and they’re trying to stay there.

“It’s going to be another epic encounter at the Den and a challenge for us because like Derby and Wolves, I expect Cardiff to be right up there at the end of the season.”

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Millwall and Cardiff are arguably two of the most physical teams in the Championship.

And Harris believes tomorrow’s contest will show Championship football at its finest. 

He added: “Any Neil Warnock team I’ve played or managed against has always been on the front foot and aggressive so I don’t think it’ll be for the faint hearted.

“We’re very low down in the passing stats in the division and Cardiff are below us. It won’t be football for the purists but it will be a good advert for Championship football.

“It will be two big sides being aggressive, going toe-to-toe and we’ll play on the front foot.

“We’ll have to raise our levels to play against Cardiff, who are by far the biggest team in the division. They’re not afraid to use their size or power.”