Dunne is part of the Premier League's meanest defence this season, with just 21 goals conceded in 26 games, and Long knows it will take something special to add to that tally today.
"Training with Richard just made me realise how good he is as a defender," said the Royals hitman. "I know I'm going to have to be at the top of my game to get near him.
"He's got everything. He's big, he's quick, he's strong, he's good in the air, he's good with the ball at this feet - he's just the all-round player.
"I know chances will be few and far between but when they do come I'll have to be on my toes."