At lunch on day three, WA were 4-336 in reply to Victoria's first-innings total of 341.

Marsh headed in with 22 boundaries to his name during his 300-ball knock, with Josh Philippe also unbeaten on 41.

WA are well placed to build a big first-innings lead courtesy of Marsh's 27th first-class ton.

He was in the form of his life two summers ago when he plundered 445 runs at 74.16 during Australia's 4-0 Ashes series victory.

But in the 19 innings since, he has only surpassed 50 once - 60 in a 31-run defeat to India in last year's Adelaide Test.

Overlooked for this year's Ashes, Marsh was part of Australia's World Cup squad before a broken arm ended his campaign.

The 36-year-old acknowledged this was the first summer in years where Test selection wasn't playing on his mind.

"It probably is, yeah. I haven't really given it any thought at all," Marsh said.

"I'm just going to really enjoy playing for WA this year. It was nice to get the hundred out there (on Saturday) and put the team in a good position.

"After my broken arm it took me a while to get a bit of rhythm back. Over the last two or three weeks, I've found my touch again and it was nice reward out there to get another hundred."

Marsh was dropped twice - first by Chris Tremain at gully on two off the bowling of Scott Boland and then by Sam Harper on 51, with the Victorian wicketkeeper unable to hold on to a reasonably difficult chance while diving to his left.

WA started Sunday at 4-256, with Marsh and Philippe adding 80 runs without loss during the morning session.

Victoria paceman Peter Siddle has 2-63 from 23 overs, while James Pattinson (1-68) snared the scalp of Cameron Bancroft (10) on Saturday.

Australian Associated Press