Test incumbent Cameron Green has pushed his claims for Ashes selection with a century for Western Australia on the opening day of the Sheffield Shield season.

Green was joined by Western Australia captain Shaun Marsh in scoring a ton against South Australia at Adelaide's Karen Rolton Oval, with the visitors 4-324 at stumps on day one.

Marsh, who won the toss and elected to bat, made 118 off 190 balls, climbing to third on the all-time Western Australian first-class run-scorers list.

Green, who made his Test debut against India last summer, scored 106 off 161 balls.

It was Green's eighth first-class century, a tally that doubles his amount of half-centuries.

He played all four Tests against the Indians, scoring 236 runs at an average of 33.71, but did not take a wicket in the series.

The 22-year-old is considered to be among the frontrunners to earn selection for the first Ashes Test, which begins on December 8 at the Gabba.

He and Marsh combined for a third-wicket stand of 199 off 46 overs after the earlier dismissals of Cameron Bancroft (11) and Sam Whiteman (44).

Given a life on 63 in the slips by South Australian captain Travis Head, Green struck 11 fours and four sixes before feathering a catch to wicketkeeper Alex Carey off paceman Nathan McAndrew.

South Australian debutant McAndrew (3-48 of 21 overs) struck again four overs later, justifying Head's decision not to take the new ball as soon as it became available.

Green struck successive sixes off leg-spinner Lloyd Pope shortly before tea to go past 50.

It was a third straight Shield hundred at the venue for Marsh and the 32nd of a first-class career that started back in 2001.

Marsh, who scored just five runs off his first 27 balls, reached his 50 with a six over long-on off spinner Sam Kerber, scoring 57 runs between lunch and tea.

Josh Philippe will resume on 28 and Hilton Cartwright on 13 on day two.

AAP/ABC