STEVE Johnson is back and so is Greater Western Sydney, with the mercurial forward kicking six second half goals in his team's 67-point rout of a tired West Coast at Spotless Stadium.

The runaway 19.11 (125) to 9.4 (58) victory books the Giants a preliminary final with Richmond at the MCG next Saturday.

Full match coverage and stats

And just one week after being dropped, Johnson was the star of the show.

With his team leading by 35 points at half-time and most of the grunt work already done, Johnson turned back the clock and gave a little dose of magic as the Giants played their best football for more than a month.

The former Cat kicked four goals in the third quarter, added two more in the last and had a late chance for a seventh goal, but failed to make the distance from 45m.

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The Giants' win ensures the top four teams will compete in next week's preliminary finals and sends a strong warning to the waiting Tigers that the path to the Grand Final will be a tough one.

The home team led at every change, dominating at stoppages, and then spreading the ball quickly to the outside where they totally outclassed the Eagles.

"I think the pressure was pretty good and we tackled well, and I think we pounced on that pressure and obviously scored off the back of it," GWS coach Leon Cameron said.

"It's always pleasing to win a cut-throat semi-final, we were disappointing last week and everyone knows that, but there's only one way to respond and that's to come out and play a pretty good brand the next week.

"Our main focus was being cleaner and absorbing pressure, and maintaining our rage with our tackle pressure, and I thought we did that pretty well."

Johnson was the polish, but he had plenty of mates doing the heavy lifting.

They led by 16 points at the first change, 35 at the half and 68 at the final break.

Every Giant rated from the first semi-final

Toby Greene was fantastic, finishing with three goals from 17 disposals, including a soaring mark over Tom Barrass in the second quarter.

Rory Lobb was excellent in the ruck against Nathan Vardy, helping his team to a 48-38 advantage in the clearances, and his midfield made the most of it.

Steve Coniglio (35 disposals and eight clearances) was arguably the best player afield, while Josh Kelly (33), Lachie Whitfield (28), Callan Ward (28) and Dylan Shiel (25) were all influential.

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The Eagles looked totally spent after their extra-time win over Port Adelaide and were outplayed from the start.

But coach Adam Simpson said he wasn't using fatigue as an excuse.

"They were exceptional tonight and we got nowhere near it," Simpson said.

"We were really disappointed, but I thought we played a team that was right on and we were a bit off.

"No, no, I wouldn't put it down to being tired.

"As the game went on, you could see that clearly we couldn't keep up on the outside.

"It didn't matter that we had to travel a couple of weeks in a row.

"We put that on ourselves throughout the season. We've got to accept that.

"Tonight we just weren't good enough. Everything we tried didn't work."

Every Eagles player rated from the first semi-final

Sam Mitchell (28 touches and two goals) and Matt Priddis (30) tried hard in their final games, while Drew Petrie kicked a goal in the last game of his career.

Retiring Eagles Sam Mitchell, Drew Petrie and Matt Priddis. Pic: AFL Photos

The Giants had a handy lead at quarter-time, but it could have been greater if they used the ball more wisely.

Jeremy McGovern and Barrass took three intercept marks each in the first term, but once the Giants stopped bombing the ball long, they had success.

Tom Scully's goal that started in the back pocket with a blistering Nathan Wilson run and scything 55m pass highlighted the superior run of the home team.

It got better – or worse for the Eagles – in the second quarter, as the home team kicked four goals to one to set up a match-winning 35-point lead.

Greater Western Sydney: The Giants look like having a fit 22 to choose from for next Saturday's preliminary final. Defender Nick Haynes had a scare in the third quarter when a clash of knees had him writhing in pain on the ground. But he quickly jumped to his feet and played out the fourth quarter. Giants coach Leon Cameron said Steve Johnson's troublesome knee would be assessed during the week, but he saw no reason to worry.

West Coast: The Eagles appeared to get through with a clean bill of health.

The Giants will play Richmond at the MCG in next Saturday's preliminary final. The teams split their meetings one apiece this season, with the Tigers easily winning in round 18 when they last met in Melbourne. The Eagles bow out in the second week of finals – one week further than last season's exit.

GREATER WESTERN SYDNEY 5.4       9.7       15.10   19.11 (125)
WEST COAST                          3.0       4.2       5.2       9.4 (58)

Greater Western Sydney:
Johnson 6, Greene 3, Patton 2, Shiel, Scully, Taranto, Ward, de Boer, Himmelberg, Deledio, Coniglio
West Coast: LeCras 2, Mitchell 2, Vardy, Kennedy, Shuey, Petrie, Darling

Greater Western Sydney: Coniglio, Whitfield, Johnson, Ward, Corr, Kelly, Shiel, Wilson
West Coast: Priddis, Shuey, Mitchell, Hurn, Redden

Greater Western Sydney: Nil
West Coast: Nil

Reports: Nil

Umpires: Stevic, Schmitt, Ryan 

Official crowd: 14,865 at Spotless Stadium