WEST Coast has suffered a huge blow on the eve of finals, with star defender Jeremy McGovern limping from the field during its clash with St Kilda due to a hamstring injury.

McGovern clutched at his right hamstring on the stroke of half-time of Thursday night's brave 15-point victory over the Saints, requiring assistance to make his way from the ground and holding his head in his hands on the bench.

>>WATCH the incident in the player above

He rallied to support his teammates at the half-time interval, but the outlook does not look good for the four-time Virgin Australia AFL All-Australian defender just 20 days before the start of finals.

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"It didn't look like a twinge," Eagles coach Adam Simpson said afterwards.

"But we'll find out in the next couple of days."

McGovern had already endured a rough evening, coming from the ground with a bloody nose in the first quarter and being forced to undergo a concussion test after a heavy knock in a marking contest.

He was cleared to return, only to hurt his hamstring with just minutes remaining in the second half. It ended his night prematurely, sidelined for the rest of the match with ice heavily strapped to his hamstring. 

West Coast already has a lengthy injury list and was missing Brendon Ah Chee (finger), Mark Hutchings (hamstring), Lewis Jetta (calf), Jack Redden (thumb), Dom Sheed (hamstring), Luke Shuey (hamstrings), Nathan Vardy (thigh) and Elliot Yeo (groin) against St Kilda.

However, the Eagles kicked the final four goals of the game to record an inspired victory that secures their ticket to the finals – and leaves the side still in the hunt to earn a double chance via a top-four finish.

"It was the best win for the club in my time here," Simpson said.

"It was really brave. Hopefully it was a good game to watch, because I think it was our youngest side for I don't know how many years. We were missing some players and the Saints threw everything at us."

St Kilda, on the other hand, let a glaring chance to qualify for the finals for the first time since 2011 slip from its grasp when it relinquished a commanding position midway through the final quarter.

The Saints had built an eight-point lead with three consecutive goals to start the final term, before conceding four straight majors to fall to an agonising defeat that leaves their finals hopes hanging in the balance.

The club must now defeat Greater Western Sydney next Friday night to ensure its passage through to the finals, but coach Brett Ratten says the side is still taking positives from the fact that its destiny remains in its own hands.

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"The good part about all of this is that the ball is in our court," Ratten said.

"We don't have to rely on anyone, it's up to us. We spoke about that after the game. We just need to do what we have to do to put a performance in that's one that we like, not one where we play bits and pieces.

"Today, we played bits and pieces against a team that was undermanned and lost players in the game. It was disappointing."