NORTH MELBOURNE 5.4 10.6 14.9 20.12 (132) FREMANTLE 2.7 7.12 12.14 14.17 (101)
Goals: North Melbourne: J Waite 4, B Brown 3, J Ziebell 3, S Gibson 3, S Higgins 2, B Cunnington, B Harvey, J MacMillan, L Thomas, M Wood. Fremantle: N Fyfe 4, H Ballantyne 2, M Pavlich 2, M Walters 2, C Mayne, L Neale, M Barlow, S Hill.
BEST: North Melbourne: Ziebell, Wells, Brown, Waite, Gibson, Cunnington, Dal Santo, Macmillan, Wright, Harvey. Fremantle: Neale, Fyfe, Walters, Ballantyne, Pavlich, Hill.
Umpires: Justin Schmitt, Jeff Dalgleish, Jordan Bannister.
Official Crowd: 23,393 at Etihad Stadium.

Undefeated North Melbourne have become clear ladder leaders four weeks into the season and made Fremantle's chances of playing off in this year's finals series more problematic.

North fell behind twice in the third quarter on Sunday but kicked six goals in the final quarter to turn a close match into a comfortable 20.12-132 to 14.17-101 win at Etihad Stadium.

The Roos are now the only unbeaten side in the competition, with Gold Coast and Sydney both recording their first loss over the weekend. It's the first time North Melbourne have been on top of the ladder since 1998, when Brent Harvey had played 38 games.

North, whose season will continue against the Suns on Saturday, also notched their fourth consecutive win for the first time since 2005.

The Dockers — minor premiers in 2016 and a finals side in all of coach Ross Lyon's four years at the club — remain winless, with a home game against Carlton to come in round five.

Jack Ziebell was a dominant player for North Melbourne, kicking two second-quarter goals as the Dockers overcame a sluggish start to level the scores late in the term.

Daniel Wells continued his return from the injuries that ruined his 2015 season, with his work-rate, foot skills and willingness to chase and lay tackles a pivotal part of North's game.

Jarrad Waite finished with four goals, with Ziebell, Sam Gibson and Ben Brown scoring three each.

Nat Fyfe kicked four of Fremantle's four goals, with Lachie Neale the Dockers' most reliable ball-winner for most of the day.

Fremantle twice hit the lead in the third term as Hayden Ballantyne and Michael Walters made the most of some more dangerous forward entries.

They grabbed the lead early in the term and again late, before Waite nailed a long set shot and followed up with a classy snap to set up a seven-point lead at three-quarter-time.

North made the much faster start to the match, scoring four unanswered goals in the first 10 minutes to put Fremantle immediately on the back foot.

Higgins and Nick Dal Santo were prominent early players for North, who were able to find space, run, carry the ball and create scoring opportunities more easily than the Dockers.

The Roos doubled Fremantle's disposal count in the first 10 minutes and finished the first term with 35 extra uncontested possessions and 11 more handball receives.

Fremantle worked their way into the game as the first quarter unfolded but struggled to move the ball as cleanly as North.

While both teams had notched nine scoring shots by the end of the quarter — North leading the inside-50 count 14-12 — North finished it with a 15-point lead.

The Dockers lifted their work-rate further in the second term, starting to win more ball and to move it into more dangerous spots going forward.

While North was still able to force errors and capitalise on them, kicking often to players open right in front of goal after getting the ball back, Fremantle gradually increased the pressure.

The Dockers scored three goals to North's two early in the term — getting the scores back to level 24 minutes in — but conceded two late goals to fall behind again.

Ballantyne, Walters, Neale and Hill became key players, with Fyfe racking up eight disposals for the term.

Ziebell turned two strong marks into goals that kept North Melbourne's nose ahead, and Wells became an influential player willing to both run with the ball and lay tackles.