New South Wales captain Michael Clarke capitalised on a costly fielding lapse to help the Blues secure first-innings points against Western Australia on the second day of the season-opening Sheffield Shield clash at the WACA Ground.

At stumps on the second day on Wednesday, the Blues were 9-358 in their first innings, an overall lead of 141 after WA made 217 on the first day.

Steve O'Keefe was 74 not out and Doug Bollinger was on five.

Clarke, who made just one in the limited overs clash between the sides on Sunday, looked in superb touch as he made 78 before slashing a Nathan Coulter-Nile delivery to Shaun Marsh in slips.

Clarke fell with just three runs needed to secure first innings points, having put on 87 for the sixth wicket with Moises Henriques, who also made 78.

It could have been a different story if Marsh had taken an earlier chance provided by Clarke from the same bowler.

With the Blues under some pressure at 5-151, Clarke got an outside edge from the bowling of the unlucky Coulter-Nile.

The ball carried comfortably to Marsh at second slip, but he grassed the simple catch.

Later in the same over, Clarke top-edged a pull shot to fine leg, where the ball landed just in front of Nathan Rimmington as he charged in off the boundary.

Coulter-Nile (2-84) also had opener Scott Henry (39) dropped in slips on 16 earlier in the day.

All-rounder Steven Smith, who made an unbeaten 99 in the one-day match, failed to replicate that form and fell to Rimmington (4-70) for a duck.

Veteran Test wicketkeeper Brad Haddin (2) lasted just 16 balls being falling LBW to Coulter-Nile.

Haddin played right across the line, but did not appear pleased with the decision.

Henriques was also adjudged LBW, to Rimmington, and was another who didn't look happy with the verdict.

WA captain Marcus North lamented the chance given to Clarke, but challenged his batsmen to bounce back in the second innings.

"It was a pretty big opportunity missed, but that happens in cricket," he said.

"Pup batted very well, they got some key partnerships and now it is important we wrap it up quickly tomorrow.

"It is a challenge to us to bat well and bat big, the game is far from over."

Henriques said the Blues had been tested by the WA bowlers, but had put themselves in the box seat for an outright win if they play well on the third day.

"We've got a good position, but it is only as good as the first session tomorrow," he said.

"That partnership with Michael and myself got us close to first innings points and then Steve O'Keefe upped the run rate and took the first innings away from them a little bit.

"Now we need to bowl as well as we can."