Dumped Test batsman Shaun Marsh holds the key to WA conjuring a miracle outright victory, resuming on nine from 55 balls alongside wicketkeeper Sam Whiteman (20) with the score at 5-138, a lead of just 34.

Marsh was hardly convincing in getting off the mark and avoiding his fourth consecutive duck, taking 12 balls to score his first run.

He failed to trouble the scorers in the first innings after back-to-back failures in the second Test of the series against South Africa in Port Elizabeth.

WA coach Justin Langer praised Marsh for showing determination to survive on a tricky pitch and ensure he will be there to help WA get itself out of the mire.

"He was a bit nervous, you get three ducks in a row everyone's nervous, but he got into gear really nicely on a really hard wicket to score on,'' Langer said.

"We know if he gets in, there's few better players in Australia, so hopefully he can get in tomorrow.

"The outfield is slow, I'd always prefer playing on a dodgy deck and a fast outfield than a flat deck and a slow outfield because at least you get value for shots.

"I'd rather play on a wicket like this where the game is going forward than a batsman's paradise.''

The Blues are likely to host the final if they win given South Australia (212), equal with NSW and WA on 26 points, is struggling in its match with Tasmania (8-507).

Meanwhile, Queensland (5-285) is looming as a chance to jump from fourth place into the decider having put itself in a strong position against Victoria (210).

NSW batsman Kurtis Patterson hoped to reduce the lead to less than 200 and capitalise on a terrific effort from the bowlers.

"If we can really drive home that advantage and not let these two blokes get set, we'll go a long way to winning the game,'' Patterson said.

"They've still got a bit of batting to come so we've got to be on our game tomorrow and not let what we've done this afternoon go to waste.''

WA put itself back in the match with an impressive bowling performance, taking six wickets in the morning session to dismiss NSW for 186.

Former Test spinner Ashton Agar was the beneficiary of some loose shots from the NSW batsman, finishing with figures of 5-74, while Canberra product Jason Behrendorff impressed with the first two wickets of the day.

Marcus North (44) and Marcus Harris (36) put WA in a strong position at 1-101, before it lost four wickets for just eight runs as NSW took the upper hand.

"Besides 30 minutes of madness we had a very good day,'' Langer said.

"The way [they fought] back from being bowled out for 82 to being back in the game.

"But as happens with the reverse swinging ball, we had a tough little period there, but there's still hope.''