Mattner, 26, said while Saturdays' 61-point loss to Carlton made making the top eight very difficult, it hadn't completely extinguished all belief of a seventh-straight September campaign for his side.
"We still have hope, but now we've got to rely on other teams and results going our way," he told afl.com.au, after the Docklands game.
"We've just got to keep winning and get back to what we've been doing in the first half of the year when we were playing some good footy.
"We've just got to get back to our style of footy and playing the way we want to play rather than worrying about other teams."
The Swans are now two games out of the top eight and possess a lowly percentage, which makes it a tough ask for them to crack into the top half of the table.
Mattner said the Swans now faced a challenge that would require some serious dedication, after playing finals nearly every season across the last decade.
"Sydney has been so good over the last couple of years in making the finals, which is the show of a really good team," he said.
"They haven't dropped down to get the draft picks or anything like that.
"It will now show in our character if we can fight and get back in the finals, or at least give it a really good run over the last six rounds."
The former Crow said he wasn't expecting anything to change with the Swans' approach across the last six rounds, despite the remote chance of a September appearance.
"We've had a couple of young guys play over the last couple of weeks, which has been good, but I guess we just have to get back to playing our style of footy and what's been working for us for the last few years," he said.
"We've probably got away from that in the last few weeks. We were good there for three weeks, although we lost games, but in the last two weeks we've been playing pretty bad as well as losing.
"We've just got to get back to our basic footy."
