Geelong's supremely talented 21-year-old defender is earmarked for the starting role tracking Sydney superstar Lance Franklin in Saturday's grand final.

De Koning has never faced Franklin, who this week re-signed with the Swans for another year, having missed this season's round two match when the 35-year-old booted his 1000th goal.

The youngster has been a revelation for the Cats this season, finishing second in the AFL Rising Star and showcasing his aerial ability while taking on top forwards every week.

Teammate Jed Bews said it was no surprise the 204cm De Koning was set to get first crack at Franklin, 14 years and 217 games his senior.

"He's a good match-up," Bews told AAP.

"They're both seven-foot tall and have got big, long arms. So I certainly won't be getting that one.

"(He can do it) and it'd be good for him. His form this year has been unbelievable, so it's just another moment for him."

But if De Koning's match-up is the most high-profile, Bews' is arguably the most challenging.

The cool-headed 29-year-old appears poised to go toe-to-toe with combative Sydney dynamo Tom Papley.

The exuberant Papley is not afraid to get in the face of opponents, but the laidback Bews remains unfazed.

"When he kicks a goal he probably gets into it a bit, which is fair enough," Bews said.

"But other than that, it's just a game. He's not too bad. I might have a different opinion next week.

"But (based on) the times that I've spent on him, he's a good player, you've just got to nullify him as best you can, he's a tricky one."

Headlined by star interceptor Tom Stewart, Geelong's defence - including the much-improved Zach Guthrie, key backs Jack Henry and De Koning, plus reliable smalls Bews, Jake Kolodjashnij and Zach Tuohy - has been a formidable unit.

Their combined strength is why Bews does not expect to handle Papley alone.

"They've got a few smalls that I'll probably go through, we don't really play a specific lock down," Bews said.

"So it'd be just start on (Papley) probably, and then just play our system and there'll be times where I'll go up on someone else, and someone else will cover him.

"If we play a good system, hopefully we'll be alright.

"But they've got a really good forward line. So we're going to have our hands full."

Australian Associated Press