The ever-reliable Drew Petrie has bagged four goals to help lead a resurgent North Melbourne to a 37-point victory over St Kilda.

After a shaky start in Hobart on Saturday the Roos finished 18.12 (120) to 11.17 (83) to produce their sixth straight win and bound on towards the AFL finals.

The Saints took to Blundstone Arena with a nothing-to-lose attitude, taking the lead early and holding an eight-point margin at quarter time, which they stretched to 20 points by the main break.

In the second phase the lacklustre Roos were largely absent from their 50 and if it hadn’t been for repeated wayward kicking and fumbles, St Kilda would have established a more commanding advantage.

But a nine-goal haul in the third quarter, of which Petrie kicked three, turned the fortune of the Roos who went to the last break with a 25-point buffer.

In the 18th minute of the third quarter Petrie gave the Roos the lead for the first time.

“Our ball use was better after half time and the forwards were higher and competed better,” Petrie said after the game.

In the middle, Todd Goldstein finished with 39 hitouts and captain Andrew Swallow had 25 disposals.

The Saints had some strong performers on show for the crowd of 14,346.

Forward Josh Bruce was a regular contributor and marked well, but with his one goal came three easy misses.

Captain Nick Riewoldt finished with two goals, while ruckman Leigh Montagna and centre David Armitage had 33 and 28 disposals respectively.