Many punters are surely scratching their heads, wondering how these clubs are playing for a place in the prelims given all the injury problems they had throughout the 2018 season.
But displaying resilience with their depth tested, these sides definitely deserve their spot in this elimination final clash.
A win for the Giants would see them contest their third consecutive preliminary final, while the Magpies are looking for a berth in their first prelim since 2012.
With two talent-laden squads, both sides are more than capable of getting the W.
Two players that will be crucial to the outcome of this clash are former teammates Adam Treloar and Toby Greene.
Treloar made his long-awaited comeback from injury against the Eagles, but failed to hit the electric heights he is capable of when at his best.
A former GWS player, Treloar shines the brightest in Collingwood's star-studded midfield.
Pies fans will be looking to him to set the MCG alight with his dash through the middle of the park.
The Giants' Toby Greene similarly made a return from a hamstring injury last week.
Unlike Treloar, Greene dominated, booting 3 goals and racking up 27 disposals.
However, it was his dangerous albeit completely legal marking technique that caught the headlines.
A player with a chequered history when it comes to in-game incidents, Greene plays on the edge, making him arguably the most exciting individual to watch in the league.
When he has started this year, the Giants are undefeated (7 wins, 1 draw).
This is why it is imperative for GWS's premiership tilt that Greene keeps his head in this high-stakes clash in front of a hostile crowd.
Ryan Griffen (GWS, likely)
Josh Kelly (GWS, likely)
A very high chance of showers, which would place a greater emphasis on contested possessions and clean ball use.
Home-ground advantage myth
A club still in its infancy, GWS are yet to establish a large traveling supporter base.
The fans that do travel from Western Sydney down to Melbourne will feel like a drop of orange dye in the ocean.
By contrast, Collingwood are the AFL club with the biggest supporter base- a supporter base that has been starved of finals appearances in the past five years.
You can bet that they will pack out the 'G, creating a vocal, intense and hostile crowd for the Giants to deal with.
However, the importance of this fact has been blown out of proportion in the media, and given too much credence by the bookies.
At the MCG this year, the Pies have already lost four games, all against top 8 teams (GWS, Richmond, West Coast and Geelong).
That's right, the Giants have already defeated the Pies at the home of footy this year, running out 16-point winners in Round 3.
What's more, is that GWS have been successful on the road this year, especially in two super-impressive wins at arguably the most hostile ground to play at for away teams, the Adelaide Oval.
With the experience of two preliminary finals at the 'G under their belt, you could even argue that the Giants will be less bothered by the spotlight and vociferous crowd than the Magpies will be.
AFL Stats Analysis: Where it will be won
Both of these teams have brilliant and evenly-matched midfields, as this table demonstrates.
With hardly anything splitting the midfield, the outcome of this game will decided on how both team's forwards and backs stand up.
Other than injuries, GWS's bane all year has been their goal-kicking accuracy.
The Magpies meanwhile have been very accurate in front of goal, leading the league with their goal accuracy percentage.
However, these numbers don't tell the whole story.
GWS played their best game of the season last week, trouncing the Swans by 49 points.
It could've been a whole lot worse for the Bloods, as GWS finished with a terrible goal kicking accuracy of 34%.
Therefore, even kicking at their usual 44% against the Pies would see the Giants fare very well.
In fact, any improvement on last week's 34% and GWS will be hard to stop, provided they maintain last week's level of performance.
The other area that may prove crucial in deciding this match is the bounce both teams are able to get off half-back.
Here, the Giants have a sizeable advantage.
Last week, GWS defender Zac Williams played his first AFL game of 2018, after a long lay-off because of an achilles injury.
Williams is a key member of the Giants' set-up, and alongside the pacey Adam Kennedy and the All-Australian Lachie Whitfield, provide dash out of defence, starting the Giants attack from down back.
Their ability to rebound 50, or get the ball out of their defensive 50, will be an important aspect to this clash.
Collingwood meanwhile don't have the same ability to move the ball quickly from half back, especially with the injuries to half-backers Darcy Moore and Matt Scharenberg.
Therefore, for Collingwood to win, they will need to turn to other avenues.
The most obvious would be Route A, which is to kick the ball to the 211 centimetres of Mason Cox.
The American import had a poor game last week, only recording five disposals and no goals.
A big game from the big man is necessary for the Pies to keep their September campaign alive.
Key AFL Stat
The Magpies have won 14 of their last 15 matches as favourites: Collingwood to win head-to-head @ $1.60
AFL Betting Tip: GWS to win head-to-head @ $2.35
Reasoning: Based on last week's performance, and the fact that they've made the prelims in their last two seasons, the Giants look set to reach the final four again.