"It will be a challenge because of the way they are playing," Cowan said of the Highlanders, currently in fifth place overall compared with the Blues' 13th.
"It was a bit different when I was there. They're playing a winning brand of rugby but when I was there they weren't quite where they are at the moment. You have to give them credit, they're playing very well.
"They put the Crusaders away last week, and they beat the Chiefs away. They're one of the form teams of the competition.
"We're looking forward to it, it's a great place to play and I've had a season under the roof there in Dunedin. I think our boys will enjoy the roof and the dry ball."
Halfback Aaron Smith emerged as a force in Cowan's final year at the Highlanders, forcing the now 33-year-old on to the bench.
It's a position Cowan finds himself in on his return, with John Kirwan preferring Jamison Gibson-Park as a starting No9 recently - although Cowan was unavailable for last weekend's victory over the Brumbies due to the birth of his second daughter.
All Blacks Aaron Smith, Ben Smith and Malakai Fekitoa have ensured the Highlanders are capable of striking when teams least expect it, as Cowan noted.
"We all know how they play, they're a very passionate bunch and if you look at last week's game they're taking every opportunity.
"They have threats right across the park, a backline that's playing very well. Aaron is leading them well at scrumhalf and you've got Lima [Sopoaga] steering the ship well too."