FREMANTLE coach Justin Longmuir says a trio of concerning injuries has taken the gloss off an outstanding first-up win against Grand Finalist Brisbane, with the Dockers’ backline depth set to be tested as they await scans on tall pair Brennan Cox and Oscar McDonald.

Brisbane, meanwhile, has lost key defender Darcy Gardiner to a PCL injury and half-back Connor McKenna to a hamstring issue in an evening of injury carnage at Optus Stadium.

The Dockers were not in a position to confirm details of McDonald's knee injury on Sunday night, after the former Carlton and Melbourne key defender landed awkwardly and hyper-extended his left leg in the third quarter.

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Brennan Cox, who played forward against the Lions, looked to have suffered a significant hamstring injury, while half-back Karl Worner was collected high in a brutal collision with Lincoln McCarthy and will enter concussion protocols.

Longmuir was thrilled with his team's maturity and fitness in weathering those setbacks and grinding out a gritty 23-point win, but injuries had left the coach with plenty of thinking to do before a round-two clash against North Melbourne.

"It's really disappointing and it takes a bit of the gloss off a really, really good win having three guys get injured like that. But it creates opportunities, and we'll have players ready to go," Longmuir said on Sunday night. 

"Karl has obviously got a concussion, so we will look after him in the early part of the week and he'll enter protocols. The other two we will just have to wait. They look pretty significant … we've just got to get a scan and we'll see how we go.

"We've got players on our list. We've got players ready to go. There's going to be opportunities for players along the journey and players are going to get some opportunities next week."

Longmuir said Fremantle had drawn on everything they'd worked on through the pre-season on Sunday, not panicking after a series of turnovers and 50m penalties left them trailing by four goals after just 12 minutes.

The coach said the Dockers' confidence was high after franking their pre-season efforts.

"We haven't been spruiking about our pre-season externally, but internally we've gone about the work," Longmuir said. "We are really confident with how fit we are, how strong we are, and the way we play. So that just probably reinforces that."

Brisbane coach Chris Fagan confirmed Gardiner had suffered a PCL knee injury after the key defender was substituted at half-time. He conceded the Lions had work to do to steady their defence.

"Conor (McKenna) is obviously a good rebound defender, so we've lost him and Keidean (Coleman) in the last two weeks," the coach said.

"Tom Doedee is available to play in the next week or so as well, so we'll give the boys a couple of days off and then get back to work again, probably on Thursday."

The Lions have a 12-day break before taking on Collingwood (0-2) in a Grand Final rematch on Easter Thursday, with the break coming at a good time for the club to gather itself.

"If we’d won those two games, I'd probably say that I don’t want that bye, but it probably will be [good timing] just to take a bit of a breath in and work out a few things," Fagan said.

"Collingwood, who played in the Grand Final last year, are struggling as well, so we've just got to find a way. We've been in this position before … we will remain optimistic. We've just got to get to work and find our form pretty quickly."