Greater Western Sydney has squandered a chance to enter the top eight, suffering an 18-point loss to Hawthorn at the MCG after Dylan Moore produced a decisive career-best performance.

The Giants, who remain in 10th spot and next face ladder-leading Melbourne, looked set to bank a percentage-boosting win after booting Sunday's opening four goals.

But the Hawks seized momentum in a fashion as striking as Tim O'Brien's second-quarter screamer, then held their nerve during a tense finish to triumph 13.12 (90) to 11.6 (72).

Moore booted four goals, including two clutch efforts in a 79-second burst that sealed the win, while 2018 Brownlow medallist Tom Mitchell grabbed a game-high 40 possessions.

Callan Ward trimmed Hawthorn's lead to just five points late in the final quarter of the topsy-turvy tussle, only for a composed Moore to slot his set shot that came with a tick over three minutes remaining.

Moore snapped another goal moments later, putting the result beyond any doubt.

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The contest was on the Giants' terms in the early stages of their first 'home' game since escaping Sydney's growing COVID-19 cluster.

But their slick ball movement and superb pressure, having been hallmarks of the youth-fueled resurgence that followed a 0-3 start to the year, dried up after Bobby Hill's second goal late in the opening quarter.

GWS went some 47 minutes without kicking a goal as Hawthorn built a 22-point lead.

Hawks coach Alastair Clarkson clattered a water bottle when Daniel Lloyd ended the Giants' drought in the third term, knowing his charges had gone close to squashing the opposition's resolve.

Stand-in skipper Toby Greene, having been unusually quiet throughout the opening half, booted two quick goals, as he and fellow stars Lachie Whitfield and Josh Kelly ignited a GWS comeback.

Hawthorn's buffer was just three points at the end of the third quarter.

Moore and Jai Newcombe's goals gifted Clarkson's side some breathing room.

Lloyd and Ward gave their side a chance of pinching the four premiership points before the Hawks steadied yet again.

The result extended Hawthorn's promising post-bye form, while the highlight was undoubtedly O'Brien's mark-of-the-year contender.

"At the peak of it, I saw the ground and it was a fair way down," O'Brien told Fox Footy.

Substitute Shaun Burgoyne, who is set to become just the fifth man in history to play 400 VFL/AFL games when he tackles former side Port Adelaide next week, entered the fray at three-quarter time.

Chad Wingard tweaked his left hamstring and was removed from the game at the final break, while Denver Grainger-Barras's debut ended in the fourth quarter because of a head knock.

Oh boy, O’Brien!
Tim O’Brien has mostly teased Hawks fans in his previous 89 matches but delivered on his high-leaping promise with a Mark of the Year contender in the second term. After Chad Wingard chipped a kick to the top of the goal square, O’Brien flew over Jack Buckley with his right shin then pushed off the 194cm defender’s shoulder to gain a second lift and send him even higher. The 27-year-old held onto the ball all the way down, then went back to kick a goal and put his team in the lead. The leap seemed to lift O’Brien’s confidence as he kicked a second major just minutes later and ended the quarter with four marks (three contested) and six kicks to go with his two goals.

The barrel is back
Perhaps inspired by Toby Greene’s 67m effort last week, Lachie Whitfield turned to the torpedo in the third term as he ran through the centre square and needed to find a way to quickly get the ball to the Giants’ stand-in skipper who was isolated against Tom Mitchell deep inside 50. Whitfield flushed the left-foot barrel on the run so well that the Hawks’ midfielder panicked and gave away a free kick to Greene, who kicked the goal and reduced the margin to three points. The torpedo was just one Whitfield’s 20 kicks in an outstanding display on a disappointing day for his team.

Denver’s debut ends early
The Hawks’ first top 10 draft pick since 2006 arrived with a reputation for taking intercept marks and flying for grabs even when deep in defence. But Denver Grainger-Barras was closer to goal when he gave an early glimpse of his talents, as he soared over a pack and threw in a twist to claim the ball in the air just outside the forward 50 arc. The 195cm defender’s day ended early when he later copped a knock to the head, but by then the 19-year-old had gathered seven disposals and four marks to show he’ll be more than comfortable at the top level.

GREATER WESTERN SYDNEY    5.1    5.4    8.6   11.6 (72)  
HAWTHORN                                2.3    6.6    8.9   13.12 (90)  

GOALS
Greater Western Sydney: Hill 2, Greene 2, Lloyd 2, Ward 2, Perryman, Finlayson, Briggs
Hawthorn: Moore 4, O’Brien 2, Worpel, Phillips, McEvoy, Breust, Wingard, Newcombe, O’Meara

BEST
Greater Western Sydney: Whitfield, Haynes, Perryman, Taranto, Kelly
Hawthorn: Mitchell, Scrimshaw, Moore, Howe, Day, Worpel, O’Brien

INJURIES
Greater Western Sydney: Nil
Hawthorn: Wingard (hamstring), Grainger-Barras (concussion)

SUBSTITUTES
Greater Western Sydney: Ash (unused)
Hawthorn: Burgoyne (replaced Wingard) 

Crowd: TBC at the MCG