Liam Scott, Josh Philippe and Mitchell Perry turned the screws on Sri Lanka A on day three to put Australia A in command of the four-day game at Darwin's Marrara Oval.
After the hosts resumed on Tuesday on 4-241 in reply to Sri Lanka A's 272 - and lost Nathan McSweeney to the day's first ball for 94 - batters six, seven and eight completed impressive half centuries to build Australia A a formidable first-innings score.
When the innings came to an end around an hour before stumps, Australia A had gone from a shaky 4-127 on day two to be all out for 486 - a lead of 214.
In reply, Sri Lanka A were quick out of the blocks with Lahiru Udara taking 12 runs from Perry off the first five deliveries of the innings.
He soon died by the sword, however, skying an attempted pull off paceman Henry Thornton to keeper Philippe on 17, before Sri Lanka A reached stumps on 1-49 off 13 overs.
McSweeney had resumed seeking six more runs for the century that would shore up his message to national selectors, after being overlooked for Australia's current tour of the West Indies.
Instead he was out on the first delivery of the morning, bowled between bat and pad by a sharp delivery from paceman Pramod Madushan (3-82) which moved back off the seam, his innings ending off 220 balls and including six fours.
McSweeney's South Australia teammate Scott began the day on 52 and added 42 more off 104 balls as he and Philippe put on 98 for the sixth wicket.
But Scott also departed for 94, this time off 221 balls, the allrounder holing out to mid-on against left-arm spinner Sonal Dinusha (4-97), who was the pick of Sri Lanka A's bowlers.
Philippe and Perry kept the runs coming in a 58-run stand before the former was trapped lbw to Nishan Peris for an aggressive 85 off 107 deliveries, with five fours and a six.
Perry continued in building a more steady 61 before he was also caught off Dinusha, mistiming a drive to extra cover, leaving Australia A 9-465.
