The Australia captain, who has a reputation for losing the toss and a career win percentage of 12.5 per cent, surprised onlookers in Canberra.
A frisbee-like technique led some to question the legitimacy of the throw, as the coin failed to spin in the air before landing on the wicket.
After winning the toss at the Manuka Oval, Paine's Australia went into bat on day one.
Following three early wickets tumbling, the hosts revived their first innings, posting 384 for four wickets at stumps.
Joe Burns (172) and Travis Head (161) put on 308 for the fourth wicket as Sri Lanka toiled.
Paine insists the side's attitude must be right as they build up to the Ashes series later this year.
"We have spoken a little bit just about our attitude and the way we turn up firstly for our two training sessions here and then tomorrow morning," Paine said.
"We had a great win in Perth against India and we turned up pretty poorly and really flat in Melbourne and started that test match pretty ordinarily.
"It's just been making sure our attitude to this test is spot on and we are leaving nothing to chance."
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