JACK Ziebell has led North Melbourne to an important 11-point win over Essendon, compounding another difficult week for the Bombers in their ongoing supplements saga.

The Kangaroos vice-captain produced one of the most clinical displays of his career at Etihad Stadium on Friday night, as the Roos winning 13.15 (93) to 12.10 (82).

He collected 29 disposals (15 contested), had 11 clearances and kicked two goals, the last of which was the sealer from outside 50 late in the final term.

The Roos improved to 4-3 for the season and jumped into the top eight with the victory, while Essendon dropped to 3-4 with the loss, falling to North Melbourne for the fourth time in their past five meetings, including last year’s elimination final.

It was a bitter end to a challenging week for the Bombers following the news the World Anti-Doping Agency will appeal the AFL Anti-Doping Tribunal's decision to clear 34 past and present Essendon players of using a banned substance.

It means the scandal, which has already overshadowed two seasons, is likely to extend well into 2015 for the embattled club.

The win could come at a cost for the Roos, who had to substitute key forward Ben Brown out of the game in the third term with a left knee injury. Fellow forward Jarrad Waite was also reported in the same quarter for striking young Bomber Zach Merrett.

The Roos weren't overly convincing, and are certainly not yet in the form that saw them progress to last year's preliminary final. 

But they withstood several Essendon challenges throughout the game and registered their fourth victory of the season, which puts them ahead of the ledger at an important stage of the campaign.

Lachlan Hansen was terrific in defence in just his second game of the year, dragging in 14 marks, collecting 24 disposals and managing to stop Essendon's forward thrusts in an array of ways.

Ben Cunnington added some grunt, Drew Petrie was rock-solid when switched into defence in the final term, and Shaun Higgins continued his strong start to his first season as a Kangaroo.

Michael Hurley's claims as one of the in-form key defenders in the competition continued, with the Bomber his side's best. Mark Baguley shut down North veteran Brent Harvey, while Dyson Heppell spent more time off half-back but was still prolific with 29 disposals and eight clearances.

The move of Jobe Watson to full forward early on was as much a surprise as it was a reprise.

The Essendon skipper, who started his career as a deep forward, booted two goals in the opening term after marks on the lead, in a positional switch that wouldn't have been expected by the Roos.

His success there early on Friday night, alongside speedster Travis Colyer who also kicked two first-term majors, added some vibrancy to a forward mix that has struggled for potency all season.

Essendon's 12-point advantage at the opening break was due to their faster ball movement, but also in part thanks to the Roos' inaccuracy; they kicked 2.6 for the term, including two shots from Waite that hit the post.

The Roos' inability to convert slowed after the first term, however, when they slammed on the first five goals of the second term and held the Bombers goalless until the final minute of the half.

The momentum shift stemmed from a contentious umpiring decision where Shaun McKernan, in his first game as a Bomber after replacing late withdrawal Jake Carlisle (neck), was not awarded a mark at the top of the goalsquare.

He was ruled to have not controlled the overhead grab – which he took in the air and pulled down to waist height before it was spilled – and the ball swung to the other end where Harvey coolly slotted his shot to give the Roos the lead.

The Bombers started the third term with another period of dominance and snatched the lead back in a quarter punctuated with huge marks from Joe Daniher and Lindsay Thomas.

The opposing pair, who have had their share of goalkicking problems, missed the ensuing shots. It was not to be the last of the drama, as North held off a spirited Essendon final-quarter charge.  

ESSENDON                      5.0    6.3    8.10    12.10 (82)
NORTH MELBOURNE     2.6    7.9    9.13    13.15 (93)

GOALS
Essendon: 
Colyer 2, Watson 2, Ambrose 2, Heppell, Goddard, Daniher, Bellchambers, Melksham, J.Merrett
North Melbourne: Petrie 2, Thomas 2, Waite 2, Ziebell 2, Gibson, Harvey, Cunnington, Nahas, Higgins

BEST
Essendon: 
Hurley, Baguley, Heppell, Goddard, Colyer, Z. Merrett
North Melbourne: 
Ziebell, Petrie, Hansen, Nahas, Cunnington, Harvey

INJURIES
Essendon: 
Langford (quad)
North Melbourne: 
Brown (knee)

SUBSTITUTES 
Essendon: 
Kyle Langford replaced by Ben Howlett at half time.
North Melbourne: Ben Brown replaced by Shaun Atley in the third quarter.

Reports: Jarrad Waite (North Melbourne) reported for striking Zach Merrett in the third quarter 

Umpires: Chamberlain, Findlay, Harris

Official crowd: 43,972 at Etihad Stadium