GWS have produced the biggest third quarter in AFL history, completely stunning reigning premiers Brisbane en route to an emphatic victory.

After leading 9.5(59) to 8.5(53) at half time, the Giants absolutely exploded in the third term, booting 14 goals and scoring a total of 86 points, blowing the game wide open.

By the time the teams paused at three-quarter time, the Lions had no answers and ended up failing to restore any pride in the 26.10(166) to 13.10(88) defeat.

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Giants players celebrate against the Lions. via Getty Images

“I can’t believe what I’m seeing,” Gerard Healy said on Fox Footy.

“They’ll gave a look at this on replay, they won’t believe what they’re putting out here at the moment. Is there a mercy rule? They are no better than witches hats at the moment.

“They’ve sat back and let their game fall apart … it’s just been an avalanche.”

Geelong great Cameron Mooney couldn’t believe what he was watching unfold.

“This is an extraordinary quarter of football from both teams … what we’re seeing from the Lions is horrifying,” he said.

“Questions will be asked of them and probably for themselves as well.”

The previous highest third-quarter score in V/AFL history came in 1982 in a clash between Essendon and Western Bulldogs.

It also marked the highest total score in GWS history with 166 points.

Jake Stringer and Toby Greene both had six goals apiece, while Max Gruzewski and Aaron Cadman finished with three each in a dominant performance.

Brisbane remain on the fringe of the top-eight with six wins and four losses, while the Giants climbed up slightly but remain well outside the finals picture.