Shuey goal after siren as Eagles edge Port

West Coast's Luke Shuey has kicked a goal after the siren to defeat Port Adelaide by two points in an extra-time AFL elimination final epic.

Shuey instantly entered finals folklore with a cool conversion from 40 metres to deliver the Eagles a 12.6 (78) to 10.16 (76) win.

"They go down in history, these types of wins," Eagles coach Adam Simpson said after Saturday night's Adelaide Oval classic.

Scores were locked 60-60 at the end of regulation time.

And the Power appeared over the line when they surged 13 points ahead in the 10 extra minutes.

Quiet for most of the night star Eagles forward Josh Kennedy then scored two clutch goals as the visitors snuck within two points, before Shuey's last-gasp heroics.

The midfielder was given a free kick when Port's Jared Polec tackled him high and, as he lined up, the siren went.

From a testing distance and 45-degree angle, Shuey kicked truly to knock Port out of the finals.

"If you had to give anyone the ball after the siren, it would be him," Simpson said.

"I was pretty confident but it's a fair pressure kick, isn't it ... no doubt, the biggest of his career."

West Coast advance to an away semi-final next Saturday night against Greater Western Sydney, after Friday night's Geelong-Sydney semi at the MCG.

And the esteemed careers of Sam Mitchell, Matt Priddis and Drew Petrie extend another week. All were valuable in the upset win.

The Eagles made the perfect start and by 10 minutes into the second term, Jack Darling had three goals and they were 31 points up.

But Port were kept in the hunt by spearhead Charlie Dixon, who kicked his side's initial three goals, and the home side reduced their deficit to 11 points at halftime.

Both sides refused to crack in a brutal third term - the only goal was scored by Port's Chad Wingard and the Eagles led by three points at three-quarter time.

In a frantic fourth term, a point to Port skipper Travis Boak levelled scores and set up the extra drama.

"I can't say that we sat there and planned in our 'what ifs' meeting this morning, what happens if it's a draw," Simpson said.

"We flicked into that mode pretty quick in the box.

"But really it was up to the players.

"And I thought both clubs were out on their feet in the last couple of minutes, trying their absolute backsides off."