Fremantle has won the AFL's Jekyll and Hyde hit-out after beating Port Adelaide by 28 points at AAMI Stadium on Sunday.

The competition's most inconsistent sides lived up to their shaky reputations with a game of swinging momentum, free-wheeling scoring and sometimes comical errors.

Fremantle came flying out of the blocks in a 39-3 first quarter, were overhauled momentarily in the second half before kicking seven of the next eight goals to open up a 27-point three-quarter time lead.

The Dockers then maintained their advantage in a hard-running, goal-for-goal fourth term and eventually won 20.9 (129) to 15.11 (101).

Despite the ebbs and flows of the match, the visitors thoroughly deserved their first victory away from Subiaco this season.

They won without their skipper Matthew Pavlich, who was a late omission from the side, and shared the workload with 16 goal kickers.

Their midfield work was also cleaner and made the most of their entries in attack.

Pavlich's replacement Rhys Palmer collected 31 disposals, Ryan Crowley had 28 touches and two goals while South Australian born Byron Schammer celebrated his 100th game with a busy afternoon.

Kane Cornes had 39 touches while Justin Westhoff and Warren Tredrea (who injured his shoulder in the last quarter) both kicked four goals.

Fremantle got off to a perfect start with Mark Johnson and Josh Carr scoring goals in the opening four minutes of the game.

Their early success triggered a dominant quarter by the visitors who did as they pleased against an undisciplined and lethargic Port.

They went on to kick four more majors for the term, Luke McPharlin chipping in with two, and kept the Power to their first goalless quarter this season.

A small but shocked AAMI Stadium crowd watched on as their team trailed by 36-points at the first break.

Dean Brogan finally got Port on the scoreboard with a tough set shot two minutes into the second quarter.

It immediately lifted the Power's confidence and they clawed themselves back into the contest.

Tredrea, who was benched after a poor first term, hit back with two contested marks and three goals while Justin Westhoff used the checkside twice to chime in with a pair of majors.

The Dockers were under the pump but a bustling Mark Johnson major and a successful Ryan Murphy set shot during the term gave them a 13-point lead at the long break.

Westhoff's height continued to worry the Dockers defence and he kicked the opening two goals of the second half.

The Power had all the momentum and when Domenic Cassisi chipped in with a running goal the home side were in front for the first time.

But the quarter was turned on its head by a resurgent an attacking Fremantle line-up.

They won several decisive centre clearances, found scoring options through their onballers and scored seven of the next eight goals.

Garrick Ibbotson scored the final major of the term to give his side a commanding 27-point margin.

It was end-to-end football during the fourth term with the Dockers responding to every Power challenge.

Mark Johnson chimed in with his third goal for the game and when Scott Thornton bobbed up for the team's 20th major, the visitors were home.

PORT: 0.3, 6.5, 11.6, 15.11 (101)
FREMANTLE: 6.3, 8.6, 15.9, 20.9 (129)

GOALS: PORT: Tredrea 4, Westhoff 4, Cassisi 2, Motlop 2, Brogan, Pearce, S.Burgoyne
FREMANTLE: Mark Johnson 3, McPharlin 2, Crowley 2, Carr, Grover, Sandilands, Murphy, McManus, Tarrant, Peake, Mayne, Mundy, Head, Ibbotson, Palmer, Thornton
BEST: PORT: K.Cornes, Westhoff, Tredrea, Cassisi, Pearce, Brogan
FREMANTLE: Palmer, Crowley, Schammer, Sandilands, Carr, Mayne, Michael Johnson,
INJURIES: PORT: Tredrea (right shoulder), Salopek (strained Achilles), Chaplin (ankle)
FREMANTLE: Nil
REPORTS: Nick Lower was reported for head high contact against Brett Peake in the third quarter.
CHANGES: Pavlich (knee) replaced in the selected side by Palmer.
UMPIRES: Stewart, Chamberlain, Jeffery
CROWD: 19,072 at the AAMI Stadium

Sportal AFL Player of the Year votes:
3. Rhys Palmer (Fremantle)
2. Ryan Crowley (Fremantle)
1. Byron Schammer (Fremantle)