WEST Coast coach Adam Simpson will explore every avenue to find a key defensive replacement for Jeremy McGovern, with a looming showdown with Sydney Swans stars Lance Franklin and Kurt Tippett on the horizon next Sunday. 

McGovern injured his left hamstring in the third quarter of the Eagles' gritty 31-point win over Collingwood at Etihad Stadium on Saturday, with Simpson expecting to lose the emerging star for about a month.

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West Coast's key defensive stocks are looking threadbare, with Eric Mackenzie and Mitch Brown sidelined for the season, and Simpson admitted the Eagles had major headaches finding adequate cover.

"We don't bat overly deep on tall defenders. Tommy Barrass has been playing at East Perth and has been playing our way. Elliott Yeo can go back," Simpson said. 

"There's a few other options I haven't thought of at the moment, which I'm going to have to because we've got some pretty big games coming up. But we can't rely on one player. 

"Our players have been standing by that all year and we've got to find a way to play without McGovern." 

WATCH: Adam Simpson's full post-match media conference

The Eagles' inaccuracy almost cost them in the 11.21 (87) to 7.14 (56) triumph – their first win over the Pies in Melbourne since 2003. 

West Coast's scoring power has been crucial to the club's shock rise to a 12-3 win-loss record, and Simpson said he would be reluctant to swing his tall forwards Josh Kennedy and Jack Darling into defence. 

"There's no point putting key forwards behind if they can't defend and if you haven't trained them up. I'd be reluctant putting Josh Kennedy behind the play," he said. 

"It's definitely an issue for us." 

The Eagles were "pretty beat up" after Saturday's win, with Scott Selwood (knee), Xavier Ellis (elbow) and Josh Hill (shoulder) all suffering the effects of a brutal contest.

Simpson praised his team for standing up under the Pies' heat in a hostile environment, although he feared his side would shoot themselves in the foot and cough up the crucial four points with their inaccuracy.

"We had so many things working well for us and we just could not convert. It's happened a few times this year for us and it's becoming a habit," Simpson said. 

"I suppose we did what we needed to do. We didn't change too much about the way that we played and we just converted a little bit better in the last quarter. 

"It's cost us games before, last year, luckily not this year."

The Eagles passed the first challenge against Collingwood in a tough stretch, but face bigger tests of their flag credentials against Hawthorn, Fremantle and a trip to Gold Coast in the month ahead.