ISAAC Heeney has revealed he played out Sydney's finals campaign carrying an injury after he struggled to compete in the Grand Final loss to Brisbane.

The Swans superstar had just 14 disposals across three quarters at the MCG on Saturday as Brisbane steamrolled to a 60-point win and claimed the premiership.

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Heeney limped off in the third quarter after further aggravating a stress fracture in his ankle, which he'd sustained before his second-half heroics helped the minor premiers secure a qualifying final win over GWS.

Key forward Logan McDonald, also playing under an injury cloud, was substituted out at the start of the third term after re-injuring his rolled ankle, while captain Callum Mills was ruled out earlier in the week with a hamstring injury.

"I've had a stress fracture in my ankle for the whole final series so I've had to manage that," Heeney said.

"After the Port game, I was pretty sore so I had to get through the week.

"I felt good going into the (Grand Final) and then I hurt it when I got run down, tackled late in the first quarter.

"I obviously couldn't get through and in the end, it was too far a deficit and I wasn't moving well. They said, 'You're done'.

"I'll go see the doctors and get a scan. We'll go from there."

Heeney's output on Saturday was well below his season average of 25.1 disposals and 5.8 clearances, with coach John Longmire conceding the early Brownlow favourite had a rare off day.

"He was a bit sore before the prelim final. He had a bit of a sore leg and he obviously played well (against Port Adelaide), but he was sore today and he didn't have his usual impact," Longmire said.

Longmire later said Heeney had a stress reaction in his shin.

It is Heeney's third Grand Final loss, following 2016 and '22.

It is also the club's fourth Grand Final loss since the 2012 flag, and comes two years after their 81-point thrashing by Geelong.

The 28-year-old, who shot to stardom this season after a move to the Swans engine room, admits the club's dominance in the home and away season with a 17-6 record only compounds their agony.

"It's a bit numb at the moment," Heeney said.

"We've been the best side of the year, and we just couldn't match it on the day that really counts, and it's upsetting.

"It's one of those days but it's happened now twice in two years and obviously happened against Port early in the year too.

"It was just not up to standard and what we hold ourselves to."