FREMANTLE coach Justin Longmuir believes the Dockers' performance against Greater Western Sydney was uncharacteristic after their winning run came to an end.

The Dockers' 14-game winning streak was ended in a surprise 21-point loss to the Giants in Canberra on Saturday.

GIANTS v DOCKERS Full match coverage and stats

Longmuir lamented his team's "off" workrate as the Giants dominated the clearance count 42 to 28 and played aggressively in their front half. 

"It was not us, it hasn't been us," the coach said.

"I thought we lacked strength in the contest, to hang onto the ball, test to tackle, all things we've been pretty good at all year."

In a further blow, Hayden Young suffered a groin injury in the second half.

It follows a spate of injuries for the 25-year-old over the last 18 months, and his loss would be another blow for the ladder leaders' minor premiership hopes ahead of a crucial clash against second-placed Sydney on Thursday night.

"We think it's just a bit of a tight groin, so we're hoping he's right," Longmuir said.

"This is what happens when you miss a lot of footy ... It can be after three or four (weeks) and something else bobs up, so hopefully it's not bad."

Jake Stringer inspired the Giants' win with a career-high seven goals, while Toby Greene had 26 disposals and kicked three goals.

Adam Kingsley had high praise for his Giants' midfield – which was led by Clayton Oliver (32 disposals and 10 clearances) – as his side improved to 7-9 and boosted its top-10 chances.

"This group's good enough. We proved that by just knocking off the best team," Kingsley said.

"I thought we played a game that we've been hoping and aspiring to play for a long period of time."