Braeden Campbell's super-sub effort at the SCG came after the death of his grandfather, while Joel Amartey and a "crook as a dog" Callum Mills were also on the cusp of missing the dramatic qualifying final against Greater Western Sydney.

 Swans coach John Longmire revealed the hidden stories of his side's stirring victory, with captain Mills pushing through a bout of gastro to get on the park against the Giants.

Amartey, who bobbed up with the match-winning goal after struggling to have any impact on the game, rolled his ankle on Thursday and Longmire explained he "didn't think he was going to play".

Campbell - who entered the fray in Saturday's third quarter as the Swans staged an almighty comeback to reel in a 28-point deficit to win by six points - had nine disposals, two tackles and a goal.

"He would have been in the 22, only he had a tough week," Longmire said.

"He lost his grandad unfortunately on Thursday night, who he was really close with.

"He was really restricted in his training (on Tuesday), had a sore groin and was barely able to get through training ... so we were tossing up whether to play him."

There were emotional scenes after the match as Campbell and sister Hannah, who works for the Swans as a trainer, were supported by teammates and Longmire on the field then in the rooms.

"To win some big 50-50 moments, be hard and clean after a pretty tough week - injury-wise and what was happening off the field - is a great credit to him," Longmire said.

"It should be a really proud moment for he and his family.

"They lost a loved one during the week.

"For them to be able to sit down as a family tonight and reflect on how BJ's grandfather impacted him and the family is a pretty special moment."

Mills singled out Campbell in his post-match address to the team on the field.

Longmire praised Amartey, who now has a fortnight to rest the ankle injury that restricted him in the clash with the Giants.

"We probably thought he might have been missing," Longmire said.

"He was just doing some extra marking on Thursday and rolled his ankle.

"'Millsy' had gastro, was crook as a dog tonight.

"Those are the stories you don't know.

"I'm sure the opposition has the same stories. When teams are in this time of the year, every team in the finals series has those.

"Sometimes you have to find a way, get through it and just get the job done."