Illawarra Lions claimed their biggest scalp for several seasons with a thumping 29-point victory over Sydney AFL first division leaders Balmain Tigers at North Dalton Park.

The eighth-placed Lions won't play finals but delivered the boilover of the year winning the first three quarters to cruise to a 12.3 (75) to 7.4 (46) triumph on Saturday.

Illawarra have beaten the top-two teams UTS Bats and Balmain at home in proof they are a wildly inconsistent side, but better than their five wins and 10 losses record suggests.

"It was a great team performance, everyone played their role and we grew in confidence the longer it went," Lions player-coach Dave Nolen said.

"A few times this season we haven't trusted our skills, particularly in windy conditions, but today we did and once we got first use of it we used it to our advantage."

Nolen admitted his side's toughness at the contest had not always been up to par, but there was no questioning their commitment against the ladder leaders.

"We weren't intimidated. We put our head over the ball, won the hard ball and got some frees which we deserved. The bounce of the ball went our way but when you win the contested footy, things do tend to run your way.

"We know we won't play finals but want to finish the season with our heads high and this performance showed that."

With a blustery breeze at their backs in the first quarter, the Lions booted five unanswered goals in a 30-point lead at the first change.

The Tigers were expected to respond in the second term but the Lions stood firm, kicking three goals to two to lead by 46 points at half-time.

Balmain had only lost two of 14 games heading into the round-15 clash but there was no respite from a rampant home side in the third term as the Lions extended their lead to 55 points.

In tough conditions for clean, precise footy, Illawarra's tactics of kicking long and direct paid dividends as they delivered their best performance under Nolen.

Stewart Boyd booted three goals, with Jake Hogarth, Dylan Koop and Mal Picken each kicking two goals.

Joel Smith was the standout in an exceptional team performance, with Boyd and Christos Panagakos also outstanding.

The Lions return to North Dalton Park on Saturday night to face another premiership contender, Pennant Hills Demons, before hitting the road for the final two games of the season.

And with a full squad to choose from, plus the prospect of three to four more first-team players available, Nolen has to make some tough selection decisions for the Demons clash.

First division ladder: Balmain 48; UTS 44, Macquarie Uni 44; Pennant Hills 36, Holroyd 36; Southern Power 24; St George 20, Illawarra 20; Uni of NSW 8; Penrith 4.