Ashton Agar had proved a handful in SA's first innings with a five-wicket haul but it was a more even WA bowling performance in the second dig as the pace trio of Joel Paris (2-10), Cameron Gannon (2-38) and Kelly (2-34) finished with multiple wickets.

Centuries to Josh Inglis, Agar and Shaun Marsh earlier in the match set up the 205-run win for the visitors.

WA batted a further 17 balls on Tuesday morning to extend their lead by 20, enough time for Cameron Green (11no) to smash a monster six over mid-wicket as Marsh (110no) ensured his 29th first-class ton was inked in red.

The Redbacks' pursuit could hardly have begun worse when Paris found the edge of opener Henry Hunt, while an inspired piece of fielding from paceman Gannon did for No.3 Brad Davis.

The athletic Gannon dived full length from cover point and returned a pinpoint back-hand flick to Inglis to catch the scrambling Davis short of his ground.

The West Aussies celebrated with glee when debutant speedster Lance Morris (1-37) snared his maiden first-class victim, with Tom Cooper chopping on for six.

SA's lower order proved harder to remove as Harry Nielsen (18 off 88 balls), Nick Winter (four off 47) and Scott ensured the match went deep into the evening session.

WA finally turned to Ashton Turner, sidelined from bowling last summer due to a shoulder injury, who needed just seven balls to get his first Shield wicket in three-and-a-half years as Cameron Bancroft took a smart catch at silly point off Winter.

Marsh's frequent bowling changes then paid off as Kelly, Gannon and Paris took the remaining three wickets to see WA join the Bulls at the top of the Shield table.