Smith rescues Australia with vital Ashes ton

A vital century by Steve Smith put Australia in a strong position and frustrated England in the third Ashes Test after they had threatened to bowl the hosts out cheaply here today.

Australia's fragile top order again stuttered as the hosts slumped to 143-5 on the first day, before Smith came to the rescue with his second Test ton in what could be the series decider.

At stumps Australia were 326-6 with Smith unbeaten on 103 and Mitchell Johnson on 39, further loosening England's grip on the trophy at 2-0 down and three to play.

Having turned the first two Tests with his fiery fast bowling, Johnson was threatening to inflict more pain on the English, this time with the bat.

Johnson had hit six boundaries as he and Smith added a quickfire 59 and counting for the seventh wicket.

Australia lead the five-Test series after big wins in Brisbne and Adelaide, and can secure the Ashes with victory in Perth.

But not for the first time in the series they found themselves in early trouble with the bat after winning the toss.

Playing his 100th Test, as was his English counterpart Alastair Cook, Australian captain Michael Clarke elected to bat on a sweltering day.

Despite the pitch offering pace and bounce, there was no sideways movement and it looked a good strip to bat on, but England capitalised on poor shot-selection by the home side.

All of the Australian batsmen, bar opener Chris Rogers (11) who was run out by a direct hit from Jimmy Anderson, fell to reckless shots.

Spinner Graeme Swann (2-71), who struggled in the first two Tests, finally made an impact when he took a good catch to remove Shane Watson and then dismissed Clarke (24) and dashing opener David Warner (60) either side of lunch.