Bennell's 27 disposals and club record-equalling six goals were a huge factor in the Suns' 40-point romp over the Cats to solidify their top-eight spot.
Harbrow believes opposition teams – starting with Hawthorn in Launceston on Saturday – will now have a target on the gifted 21-year-old's back.
While admitting the West Australian was on a "different level", the cool-headed Harbrow said Bennell had to keep his feet on the ground.
"We don't want to get too carried away at this stage," Harbrow told AFL.com.au.
"I know he doesn't want to get pumped up too much, because he knows he'll get a lot of close attention from opposition coming up.
"We've got a couple of tough weeks coming up and he's going to get a lot of attention.
"His class and how he sees the game is a different level to most players."
Harbrow was a major influence on Bennell's early life at the Suns, housing the homesick teenager after Karmichael Hunt and his wife Emma had started to right the ship.
Bennell now well and truly calls the Gold Coast home and recently signed a contract that will tie him to the club until the end of 2017.
Harbrow said Bennell had always had a good work ethic and attitude, and Saturday night was a reward for that.
"It was on the back of his work rate. He went into the game with a defensive-mind focus," he said.
"His class and hard work offensively will play out naturally. His goals came off the back off his defensive efforts.
"He's not always going to have a massive game like that, but someone else will pop up next week and the week after."
Twitter: @AFL_mikewhiting
