Thompson had been earmarked for defence since a late switch in 2011, but an injury-destroyed 2012 curtailed his progress.
On Saturday night, he showed McKenna he was the man to take the key defensive post alongside Matthew Warnock with an admirable effort against Hawthorn superstar Lance Franklin.
Admittedly Franklin was in second gear at times, but when challenged in a one-on-one contest, 20-year-old Thompson invariably won.
The Southport product was drafted by the Suns as a forward/ruckman, but quickly showed he was well equipped to handle the back half.
However he had groin surgery at the end of 2011, and then after five games in the seniors last year, rolled his ankle and ultimately required surgery on that as well.
This year he has completed a good pre-season, added some requisite size, and now looks a key component in solidifying a developing back six.
"Hopefully I can be the key defender down there, centre half back or fullback," Thompson said.
"That's my goal, to play on the best forward every week."
The Suns are blessed with speed and young talent in the midfield and have a host of tall forwards they are developing but the back half has been the major concern the first two years.
Consequently they traded for Warnock at the end of 2011 and also lured Fremantle's Greg Broughton and Hawthorn's Tom Murphy to Metricon Stadium last October.
Thompson said learning from that trio along with recovering vice-captain Nathan Bock, was invaluable.
"It's been really good. I'm getting plenty of on-field coaching from them," he said.
"They help us young boys know where to go and help us become leaders, so we can direct each other out there a lot more and be a tighter group out there.
"It's just a lot of little things, like sharing their knowledge. If you run to the wrong spot or make the wrong decision, they'll pull you up and tell you what you should be doing or thinking in that situation."
Thompson, who stands 200cm, should face another stiff challenge on Saturday when the Suns tackle the tall forward line of North Melbourne in Townsville.
Rory Thompson is a defender in NAB AFL Fantasy. He averaged 48 points in 2012. Register your team at our AFL Fantasy Hub.
Michael Whiting covers Gold Coast news for AFL.com.au. Follow him on Twitter: @AFL_mikewhiting
