The Kangaroos' undefeated streak is now 32 games, having started their premiership defence with three victories to sit atop the ladder.
Sydney have also maintained a perfect start under new coach O'Riordan, sitting fourth behind third-placed Carlton and next-best Melbourne.
But the Kangaroos are the clear frontrunners on the ladder, boasting a percentage of 257.8 in comparison to Sydney's 150.
North Melbourne's ruthless start has prompted punters and critics to predict a fourth consecutive grand final appearance, perceiving Melbourne as the only true threat.
Meanwhile, there are still four teams yet to register a win - West Coast, Essendon, Collingwood and last-placed St Kilda.
But O'Riordan says it's too early to call the competition, adding he's far from concerned the chasm between the best and the worst is becoming more pronounced.
There has been some shift in the league's top order, with long-time heavyweights Brisbane and Adelaide managing just one win each to sit outside the top eight.
"The games that the bottom four have been in, they've been really tight," O'Riordan said.
"Sometimes the ladder can do a disservice to what the actual game looks like.
"It'll be interesting to see how it goes in the next three weeks and when it starts to take shape.
"At the minute, it's actually been really even competition for a large extent."
O'Riordan pointed to last week's clash between the Western Bulldogs and the Kangaroos, despite a 47-point win to the reigning premiers.
An injury-hit Sydney are set to travel to Whitten Oval after a 23-point triumph over the Saints.
The Swans will have to wait until round eight to face North Melbourne and won't play Melbourne in the home-and-away season this year.
"North are obviously a really good team, but I actually thought in probably the first quarter and even the first half, they (the Bulldogs) matched them, if not bettered them in a lot of areas," O'Riordan said.
Star recruit Taylor Smith, having cut a four-week recovery from a fractured wrist to just one week, Tanya Kennedy (back), Holly Cooper (elbow) and Jas Grierson (calf) are a chance to return.
Sydney's women are out to maintain an undefeated start as the club navigates a police investigation into sexual assault allegations and a crisis in the men's team, with five players - Isaac Heeney, Chad Warner, Nick Blakey, James Jordon and Riley Bice - suspended for the rest of the AFL season for breaching club standards.
No charges have been laid by police and AAP is not suggesting any criminal wrongdoing.
"Their ability to show resilience in tough moments, whether it's on-field or off-field, is something I'm incredibly proud of," O'Riordan said of the women's team.
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