NORTH Melbourne backman Scott Thompson is now the equal of any key defender in the competition, teammate Michael Firrito says.

Thompson has started the 2013 season in outstanding form, holding Brisbane Lions captain Jonathan Brown, Hawthorn spearhead Lance Franklin and key Sydney Swans forward Sam Reid goalless.

He has also given North plenty of drive from its defensive 50, averaging 20 possessions, more than four rebound 50s and two contested marks a game in the first six rounds.

Thompson, who turns 27 on Thursday, will play his 100th AFL game on Saturday against the Western Bulldogs.

Firrito, who is set to play his 200th AFL game on the same day, told AFL.com.au this week that Thompson's ability to stifle his opponent and win his own ball made him an invaluable player for the Roos.

"Obviously we're his biggest fans and we're probably biased, but Scotty is definitely in All Australian form at the moment," Firrito said.

"He's a fantastic competitor, he's so good one on one, he can beat his direct opponent, and there are not many key defenders in the comp who are as damaging the other way as he is with his rebounding and intercept marking. 

"He's as good as any defender in the competition at the moment. He's the complete package, so he's great for our backline and he'll soon be known as one of the elite defenders in the competition.

"We think he already is."

Firrito heaped even more praise on his fellow defender, saying Thompson's early-season form had been the equal of any North defender he'd played with in his 11-season career.

It's a big statement when you consider Firrito has played alongside former Roos greats such as Glenn Archer, David King, Jason McCartney, Leigh Colbert and Brady Rawlings.

Former Roos skipper Brent Harvey also sung Thompson's praises at Aegis Park on Wednesday, agreeing that Thompson was on track to make the All Australian team.

"He's been absolutely sensational," Harvey said. 

"Last week (against Port Adelaide), it was actually great to sit back and watch some of the things that he does. 

"We all know that his defensive work is fantastic, but to see the way he runs off and creates some forward thrusts for us is really good, and he's certainly in All Australian form."

Firrito said Thompson had been unfairly cast as a limited, niggling defender after bumping Western Bulldog Barry Hall while Hall was tying his bootlaces in round nine, 2010.

Firrito said Thompson was a far better player than most had given him credit for at the time, and had since got even better. 

"He copped a fair whack for the Barry Hall incident, I think the public perception definitely went against him," Firrito said. 

"But he's a fantastic player, and anyone that's seen our season so far and his season last year would have seen how much he's improved.

"He still tends to fly under the radar a lot, but while he's probably not getting the recognition he deserves at the moment, I'm sure other teams and the wider football community will soon be noticing him."