Nothing lasts forever.

On July 17, 2016, Sydney and Hawthorn met at the SCG in a blockbuster top-of-the-table clash. The two heavyweights had played off in two of the past four Grand Finals. The Hawks were three-time reigning premiers. The Swans were the last side to beat them on Grand Final day.

Just 10 months later they meet on Friday night at the same venue with identical records of 3-6, two games outside the top eight. The loser can all but book a September holiday, despite the incredible unpredictability of this AFL season. The winner's finals hopes stay alive, but they still have a mountain to climb.

It's amazing how much has changed since last July. The Hawks won that epic by five points to go a game clear on top of the ladder while the Swans slipped to fifth, such was the tightness of the 2016 premiership race. The Hawks were eventually ousted from the finals in straight sets, although they were a kick away from a preliminary final. The Swans led the Grand Final at half-time but lost to the Western Bulldogs.

The Round 17 game was the heavyweight bout it was billed to be, ebbing and flowing with eight lead changes before Shaun Burgoyne dragged the Hawks over the line with a phenomenal last quarter.

Cyril Rioli celebrates with Isaac Smith and Brad Hill during the epic clash against Sydney in 2016. Cameron Spencer/Getty Images

While Burgoyne remains a key figure at the Hawks, a number of their match winners that night are no longer there. Sam Mitchell had 37 touches and polled two Brownlow votes but will line up for West Coast this week. Jordan Lewis gathered 26 disposals and kicked a goal and is preparing for Melbourne's clash with Gold Coast. Bradley Hill had 25 touches and kicked a goal but is now starring for Fremantle. Cyril Rioli (two goals), Grant Birchall (25 disposals) and James Frawley are all sidelined with injury.

Tom Mitchell was the Swans' leading ball winner with 37 disposals in that game. He will now return to the SCG in Hawthorn colours coming off 50 disposals against Collingwood last week.

(Photo by Michael Dodge/Getty Images)

Last year's encounter bares little relevance to this week but that doesn't make it any less fascinating.

This is unfamiliar territory for these two mighty clubs. Neither team has missed the finals since 2009. The last time these sides met in such circumstances was Round 11 of that season. Both sides were 5-5, the Hawks were the reigning premiers in danger of missing the eight while the Swans had not missed the eight for six straight seasons.

Two-time premiership Sydney midfielder Jude Bolton played in that game and has no recollection of it, a by-product of playing at a club that perennially contended.

But Bolton told ESPN the mindset of a team in danger of missing the eight is far different to that of one entrenched in the top four.

"I think losing early games in the season puts enormous pressure on and you can capitulate under that pressure," Bolton said.

"Everything has got to go so right for you to try and bank those wins through the middle of the season and there's a compounding thing with injuries as well during the winter months.

"I think we just turned over a list through that period and had to try and regenerate and we just weren't playing well enough as a team. It's incredible how quickly it can envelop you in terms of a loss of confidence and loss of form."

Bolton feels the Hawks are in a similar head space while the Swans are in a slightly different scenario. That is evidenced by the change in personnel. The Swans had 16 of the 22 that played against the Hawks last year on the park against St Kilda last Saturday, but the top seven from their 2016 best and fairest count were all there. The Hawks had 10 of their 22 missing last Saturday against Collingwood, including four of their top five in last year's best and fairest.

"I feel the Swans are probably in a better position on Friday night," Bolton said.

"The Swans have got some young talent in there and have got some games into them. I feel it was a little bit of a perfect storm for them at the start of the year. They always start fairly slow the Swans after going deep in September but when they had a run of injuries to some key players, and I'd say Dane Rampe is one of the most critical players for them, just suddenly all these young guys were under enormous pressure and they suffered those back to back losses. But I feel that they're probably getting a stronger list back together now."

The Hawks can never be discounted and the Swans are wary, with Lance Franklin saying as much this week.

Photo by Quinn Rooney/Getty Images

But how the Hawks approach the rest of the year given the personnel changes is intriguing.

"They are in an interesting situation," Bolton said.

"They've been through such a run of excellence and had such an incredible run of success that now when they've tried to make those changes and get guys like Tom Mitchell and Jaeger O'Meara in to keep going and keep up there, it hasn't worked out.

"Some of (the older) guys have dropped away a little bit and now they sit not being able to rejuvenate without a first-round pick as well. I think there's a little bit more downturn still to come. It will be a tough period for their club to go through but Alastair Clarkson is the man to guide them through."

Nothing last forever. But the more things change the more they stay the same. The Swans and Hawks might not be playing for premiership favouritism this week like they have so often in the recent past. But there will be plenty on the line nonetheless.