FREMANTLE coach Justin Longmuir says he has concerns around player safety on the SCG surface but will be led by the AFL as his team prepares to take on Sydney next Sunday.  

The 10-5 Dockers are chasing a seventh straight win next week after lifting late to beat St Kilda by 12 points on Sunday, but there is conjecture around whether the Swans' home is suitable to host the match.

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Longmuir said the AFL had approached Fremantle and were looking into the turf issue, with players in Friday night's clash between the Western Bulldogs and Sydney struggling to keep their feet on a surface that has been described as unacceptable.

Heavy rain is expected in Sydney this week, including up to 90mm on Tuesday, potentially hampering efforts to revive the surface, which has struggled to bounce back after hosting an Andrea Bocelli concert in April.

"I watched the game on Friday night, and we'll be led by the AFL. But the moment my brain goes to, 'That's unsafe for players', I have a concern," Longmuir said on Sunday night.

"I went there on Friday night. I thought at times it was unsafe to play on.

"We just can't put players out there and risk their safety if the ground's not right, and I thought it was a bit unsafe the other night, especially down the left-hand side.

"I don't make those decisions and fully understand that both teams are playing on the same surface.

"So, if the AFL deem it safe to play, we'll play, and I won't speak another moment of it. But I thought it was unsafe the other night."

Asked if the Dockers would approach the League with their concerns, Longmuir said: "The AFL approached us and they're going to look at it, like they should. They've got the experts and we will be guided by them". 

Dual Brownlow medallist Nat Fyfe is in doubt for next week's clash after experiencing "calf awareness" while warming up as the substitute at half-time against the Saints on Sunday.

Longmuir said the Dockers had taken the safe approach to not inject Fyfe into the game given they didn't have to.

"He tried to warm up at half-time and did some run-throughs, and then he felt some awareness in his calf," Longmuir said.

"Not sure whether we could have put him on if we had an injury, but since we didn't have an injury and didn't have any players really flagging, the safe option was to just leave him out of the game.

"It's a bit of a concern, of course, but we'll see how he pulls up tomorrow, get it scanned if we need to, and see where it takes us. But from what I understand, it's pretty minor."

Longmuir paid tribute to the performance of ruckman Sean Darcy, who was "dominant" in the final quarter with 12 hitouts, three clearances and a goal, while sidekick Luke Jackson went forward and booted two goals.

"There were a lot of contributors in the last but I thought our talls, and in particular our rucks were dominant," Longmuir said.

"Sean was having more impact in the ruck for us and we opted to give him more minutes in the last quarter, and the great thing about Jacko is he's able to impact in other areas of the ground.

"Jacko had direct impact in three of the five goals in the last. It was a good performance for him, when it wasn't probably going his way in the ruck and midfield, but he was able to impact as a forward."

Longmuir described the win as a "mature performance", working through the challenge of a congested midfield as the Saints sent numbers to the stoppages and made life difficult for Caleb Serong and Andrew Brayshaw.

"We knew what sort of game we were going to get. We knew it was going to be frustrating at times, but I thought we worked through that as a team and individuals," Longmuir said.

"To get on top I think with +9 clearances in the last quarter is testament to our maturity and our ability to problem-solve, and that's what's taken a massive step forward in the last six weeks since we played them last time."

St Kilda coach Ross Lyon said his midfielders had not played lockdown roles but perhaps just matched up well on the Freo onballers and competed hard.

Coaching in front of Fremantle fans for the first time since his eight-season tenure at the club ended, he said returning to Perth to take on the Dockers was not something that had occupied his mind.

"I was a Saint first, right? So it does feel like home, but to see (Matthew) Pavlich and (Nat) Fyfe … culture, is about the people that you work with on a daily basis," he said.

"Whether it was Mark Harvey or me, or Chris Connolly, or whoever it is, or Longmuir when he goes, … you do your best, and then hopefully you're part of that club's history and it's respected."