Australia's DRS woes have cost Pat Cummins's men a crucial chance to claim the ascendancy in Galle, failing to review an lbw shout that would have removed the dangerous Dimuth Karunaratne before lunch on day one.
Both Cummins and Mitchell Starc claimed a wicket in the opening two hours on Wednesday, sending the hosts to lunch at 2-68 on the first day of the series.
Cummins in particular bowled well, beating the bat several times before getting Pathum Nissanka caught behind with one that bounced a bit more on 23.
Starc got rid of Kusal Mendis for three on the first ball of his second spell, luring him into a drive wide outside off stump.
But it's the missed review Australia could live to regret.
Karunaratne went to lunch on 25no after he went back to pull a Swepson ball that stayed low, and while Australia discussed it they did not refer the on-field call of not out.
Replays showed the ball would have crashed into leg stump.
Karunaratne is easily the hosts' best batter, averaging 60.8 over the past 18 months.
Australia also need everything to go in their favour after losing the toss on one of the most advantageous wickets for spinners in world cricket.
Teams from outside the sub-continent have won just two of 16 matches batting last in Galle, battling with a wicket that turns more as the match goes on.
Already there has been sign of plenty of assistance for the tweakers.
Nathan Lyon got significant bite out of his first ball, drifting in and then ripping past Karunaratne's off-stump and into Alex Carey's nose.
He has looked ever dangerous with Marnus Labuschagne putting down a tough chance off the face of the bat in close with Karunaratne on 15.
Sri Lanka have picked four spinners for the series opener and just one quick, after their slower bowlers took 54 wickets across three Tests on Australia's last visit in 2016.
Australia meanwhile have gone with two spinners and will use Labuschagne and Travis Head as part-time turners, after the latter overcome a hamstring injury to play.
