Chris Fagan has urged the umpires to protect the man with the ball, claiming his Brisbane players were punished for lowering their height to collect possession during their defeat of Fremantle.

The Lions dominated the Dockers on Saturday at the Gabba to rack up a fourth-straight win and improve to 5-2.

But they have two injury concerns in Dayne Zorko (hamstring) and Daniel Rich (calf) ahead of Friday's clash with Carlton in Melbourne, Zorko's of particular concern given he battled a hamstring tendon injury in the pre-season.

The former captain had earlier been cleared of concussion and was able to play on after a slinging Matthew Johnson tackle sent his shoulder and head thundering into the turf.

Johnson had already been penalised for high contact and was placed on report for the second movement that brought Zorko to the ground.

But a concerned Fagan believed other incidents, including tackles on Cam Rayner and Hugh McCluggage, went unpunished because the umpires thought they were playing for a free kick.

"That was a pretty vigorous sort of tackle," he said of the Johnson tackle.

"I don't normally comment on umpires but I don't think they protected the head all that well.

"I was a bit surprised a few high tackles were called play-on."

He said players who lower their height to gain possession should be rewarded.

"The responsibility of the tacklers is not to get the bloke around the head," Fagan said.

"It seemed to me, and I might be wrong, that the umpires were trying to interpret whether or not the bloke was ducking his head and deserved to be tackled in that manner.

"The bloke with the ball needs to be looked after."

Fagan was otherwise pleased with the Lions' ability to snuff out Fremantle's early onslaught as the out-of-form side attempted to blaze their way through the corridor in a handball frenzy.

Brisbane led by 31 at halftime, Lincoln McCarthy and Joe Daniher both kicking three goals and Lachie Neale collecting 35 disposals and 13 clearances.

Their only blemish came in conceding five of the Dockers' 10 goals in the third quarter, but Fagan said it was the players themselves who addressed that at the final break.

"I thought we tried to be a bit too flashy at times and paid a bit of a price for that, but outside of that played the way we wanted to play," he said.