Fremantle returned to the winners list and dealt a hefty blow to Port Adelaide's top-two ambitions with an upset nine-point victory at Optus Stadium on Sunday.

Port came into the mistake-riddled contest riding a five-game winning streak but wasted a dominant opening term and left the door open for Freo, who snuck through for a morale-boosting 8.11 (59) to 7.8 (50) triumph. 

It was a golden opportunity missed for the visitors, who could've finished the round only percentage off League-leader Richmond but have now dropped to fifth spot on the ladder.

Meanwhile, the rebuilding Dockers will feel good about themselves again after notching a seventh victory in 2018 and putting two disappointing performances since the bye against Brisbane and Melbourne behind them.  

"I thought (it was) really pleasing. We disappointed against a quality team in difficult conditions last week," Freo coach Ross Lyon said post-match.

"I thought we competed really strongly, we wanted to be harder to play against and 58 entries to 39 against a top-four team speaks volumes for how intense we were and how we competed fiercely.

"Our accuracy will get better. Port Adelaide never gave up. I thought it was pleasing, a real step forward."

In a game marred by basic skill errors, Freo found avenues to goal after half-time, booting seven of the first nine majors to hold a 22-point lead at the 15-minute mark of the final term.

The Power tried to mount a late surge but Brad Ebert and Lindsay Thomas fluffed their lines in tough shots and failed to score, summing up a forgettable trip west.

The Dockers lifted after a poor opening quarter and had 20 attacking entries but missed several opportunities, booting seven unanswered behinds.

Brennan Cox's second goal at the 12-minute mark of the third term drew cheers from the 33,190-strong crowd after he snapped a run of nine behinds in a row.

The only real highlight of the first half came early when Chad Wingard drew first blood with a sublime Goal of the Year contender, a checkside from hard up on the boundary.

The Power could have had the game by the scruff of the neck at the first break, but couldn't capitalise on dominance in clearances (20-4) and contested possessions (55-29) and only led by nine points.

It came back to haunt them, with the Dockers finding a way to notch a sixth win from nine games at their new home ground.

In superstar Nat Fyfe's absence, Lachie Neale stood up in the midfield with 34 touches and nine clearances, while veteran David Mundy (29, one goal) and Ed Langdon (28) were influential, and Luke Ryan (28, seven rebound 50s) continued his excellent season across half-back.

Wingard was Port's only multiple goalkicker with two majors, to go with 24 touches and seven clearances, while midfield bulls Ollie Wines (30 disposals and five clearances) and Sam Powell-Pepper (28) could hold their heads high.

MEDICAL ROOM
Fremantle: Cam McCarthy came from the ground clutching his hip during the second term but played out the match. Sean Darcy limped off the field during the final term. 

Port Adelaide: Star ruckman Ryder was done for the day after coming off in the second term with a right hip flexor issue. Gray was out cold after his head hit the ground in a Ryan Nyhuis tackle early in the second half, while Riley Bonner limped off the ground late in the third term.

NEXT UP
The Dockers travel to Etihad Stadium to face Essendon in a must-win game for the Bombers' finals ambitions on Saturday, while Port Adelaide is facing a crucial contest against the resurgent Giants in an Adelaide Oval blockbuster next Sunday.

FREMANTLE                       1.0      1.7      5.10    8.11 (59)                  
PORT ADELAIDE                2.3      2.3      4.6      7.8 (50)           

GOALS
Fremantle: Cox 2, Sutcliffe, Hughes, Jones, Mundy, McCarthy, Walters
Port Adelaide: Wingard 2, Westhoff, S.Gray, Powell-Pepper, Watts, Boak

BEST 
Fremantle: Mundy, Neale, Ryan, Langdon, Cox, Darcy
Port Adelaide: Wines, Polec, Powell-Pepper, Wingard, Westhoff

INJURIES 
Fremantle: Nil
Port Adelaide: Ryder (hip flexor), Gray (concussion)

Reports: Nil

Umpires: Schmitt, Whetton, Mitchell

Official crowd: 33,190 at Optus Stadium