Fremantle skipper Nat Fyfe has copped a sickening concussion as the Dockers overcame a late scare to beat St Kilda by five points in their AFL clash at Optus Stadium.

The Dockers ended up holding off the visitors for a 11.5 (71) to 9.12 (66) victory on Sunday.

Fremantle initially looked set for an easy victory after opening up a 31-point lead early in the second quarter.

But the Saints clawed their way back into the contest, and scored two late goals to close to within five points with just eight seconds remaining.

St Kilda tried to flout the 6-6-6 law by throwing an extra player forward at the final bounce, but the umpires were aware of the ploy and called the Saints player back to his right spot.

Fremantle won the ensuing centre bounce to the seal victory.

Fyfe’s day ended midway through the third quarter when he clashed heads with St Kilda’s Josh Battle.

The star Docker lay dazed on the ground for more than a minute, and was so concussed that he couldn’t stand up by himself.

Two trainers had to effectively carry Fyfe from the field given how wobbly he was on his feet.

The heavy hit puts Fyfe’s availability for next Saturday’s western derby in doubt.

Fremantle forward Jesse Hogan could come under scrutiny for a head-high bump on Nathan Brown in the second quarter.

The pair were running side by side chasing a loose ball when Hogan delivered a hip-and-shoulder that caught Brown a tad high.

Brown went to the rooms for assessment, but was able to return in the third quarter.

Michael Walters starred for Fremantle with 27 disposals, eight clearances and two goals, while Luke Ryan (32 disposals) was a rock in defence.

Jack Billings notched 32 touches and two goals for the Saints, with Jade Gresham (20 disposals, two goals) also important.

The first term was a scrappy affair littered with ugly errors from both sides.

Fremantle won the inside 50m count 20-6, but their helter-skelter entries made it tough for the forwards.

The class of Walters in tight helped clear some of the congestion, with the Dockers edging to a 13-point lead at quarter time.

Goals to Rory Lobb, Ethan Hughes, and Matt Taberner looked set to blow the game wide open as the lead ballooned to 31 points.

But St Kilda launched a strong comeback, booting the last four goals of the half to reduce the margin to five points.

The Saints trailed by six points following a third-quarter arm wrestle, but two early goals to Matera in the final quarter gave Fremantle the winning edge they needed.

Matera finished with three goals, but Hogan was scoreless from his 16 disposals.