Victorian paceman Fergus O'Neill has snared 5-47 to put the Bushrangers in the box seat in their Sheffield Shield clash with South Australia.

The Redbacks were bowled out for 271 in their second innings at Junction Oval on Monday, setting the Bushrangers a victory target of 157.

Victoria went to stumps on day three at 2-49, with the home side needing another 108 runs to secure the win.

Nic Maddinson, who scored 104 in Victoria's first-innings total of 288, is unbeaten on 21, while Xavier Crone (yet to score) also made it to stumps.

Victorian opener Marcus Harris only made four before being bowled by Nathan McAndrew (2-18).

Nightwatchman Todd Murphy (18) was then trapped lbw by McAndrew in the final over of the day.

The opening session on Monday was washed out by rain.

When play resumed after lunch with South Australia 2-66 in their second innings, Victorian paceman Scott Boland was able to take his place on the field after passing a fitness test on his sore knee.

O'Neill, the Bradman Young Cricketer of the Year, dismissed Jake Carder late on Sunday, then claimed another four wickets on Monday to put the brakes on South Australia's second innings.

The 23-year-old snared the key scalps of Henry Hunt (54), McAndrew (43) and Harry Nielsen (67), before finishing off his fine haul with the wicket of Ben Manenti (19).

Spinner Murphy snared 3-54 and Boland chipped in with 2-35 from 16 overs in a strong bowling display from Victoria.

"It's pretty phenomenal. He's just gone from strength to strength," Murphy said of O'Neill.

"He had a hell of a first half of the year, and to pick up where he left off in this match is awesome.

"We're in quite a strong position. Hopefully we've taken the sting out of the new ball there."

Nielsen hasn't given up hope of South Australia stealing victory.

"We're a little bit behind the game, we know that," he said.

"We're going to have to come here tomorrow to bowl well.

"But a day-four wicket, it's keeping a bit low - there's enough there for us if we can bowl well."