Western Australia have declared their first innings with a lead of 469, shortly after Liam Davis brought up a superb triple century on day three of the Sheffield Shield clash against NSW at the WACA.

After losing partner Adam Voges early in the session to end a mammoth 379-run, 456 minute partnership, Davis took to the NSW attack and belted three sixes on his way to the milestone.

He finished 303 not out as WA declared at 3-560 and NSW have been sent in to face a testing 15-minute period before lunch.

Davis would not have reached 300 had Timm Van Der Gugten held a sitter on the boundary with Davis on 299, before the ball spilled over the rope.

WA immediately declared.

Earlier in the session, Nathan Hauritz finally ended the Davis and Voges partnership, with Brad Haddin taking a sharp catch behind the stumps to dismiss Voges for 178.

In the quest for quick runs, Davis took 21 off one Hauritz over, which included two sixes and two fours.