PORT Adelaide great Kane Cornes says the form of skipper Tom Jonas is "an elephant in the room" as the Power looks to plug holes in the League's leakiest defence.

The Power's 31-point loss in the Showdown on Saturday night, which followed a thumping defeat at the hands of Collingwood in round two, has taken the gloss off their opening round win over Brisbane and left them with a 1-2 record ahead of a trip to Sydney this weekend to face the Swans.

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Chief among Port's concerns is its defence, which has conceded an average of 108 points this season, the highest in the competition.

Adelaide duo Riley Thilthorpe and Izak Rankine combined for nine goals in the Showdown, with Cornes highlighting several "ordinary, fumbly errors" from the Power that led to Crows goals.

With Jonas (188cm) and Aliir Aliir (193cm) their only tall defenders of note, two-time All Australian Cornes is concerned his former side will continue to be exposed down back.

"Their defence was sloppy, they're far too small in defence, which we knew prior to the start of the season, and Thilthorpe got a hold of them," Cornes said on AFL.com.au's The Round So Far.

"The effort and the intensity was there, but moments like that (fumbles) has been what's cost them. They haven't been good enough around the ball and they haven't had enough contributors.

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"Tom Jonas is really down on form, the captain. There's a bit of an elephant in the room with what to do with him as skipper, and their defensive structure is all at sea.

"There was some good (against Adelaide) and they played some really good footy, but in the end they don't look anything like a top-eight side."

After the Power were exposed by Collingwood's forwards at the MCG in round two, Cornes had called for out-of-form forward Mitch Georgiades to be moved into defence to help plug a hole.

But coach Ken Hinkley instead dropped Georgiades altogether for the Showdown as ruck-forward Jeremy Finlayson made his return from injury.

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With defenders Ryan Burton (suspension) and Trent McKenzie (injury) still sidelined, the Power will have to respond on Saturday night against a Swans forward line featuring Lance Franklin, Logan McDonald and Joel Amartey.

Essendon great Matthew Lloyd says the Power have issues all over the ground, which will be of concern for Hinkley given he's uncontracted beyond this season.

"You just can't trust them," Lloyd said on AFL.com.au's Access All Areas.

"Jason Horne-Francis, his first game (was good), but you can't trust anything he's done in week two or three. That backline, you can't trust any of them.

"It's a real worry for Ken Hinkley given the pressure he's under."