Dinesh Chandimal has scored an unbeaten 63 as Sri Lanka struggled to 136-5 at lunch on Day 3 in reply to Australia's imposing first innings of 654 in the first cricket test.

Australia's Usman Khawaja struck a maiden double hundred and Josh Inglis got a century on his test debut against Sri Lanka to power the tourists to a mammoth 654 for six before they declared their first innings on day two of the opening test on Thursday.

Travis Head takes one of the best catches of his career as Australia takes three wickets in the final hour of day two to further turn the screws against Sri Lanka in the first Test in Galle.

Australia may be about to enter a new era of overseas Test cricket on free-to-air television as Seven prepares to broadcast the Sri Lanka series starting this week, a harbinger of future bidding for matches in India and elsewhere.

Travis Head will replace Sam Konstas as Usman Khawaja's opening partner in the first test against Sri Lanka at Galle on Wednesday, Australia's stand-in captain Steve Smith said on the eve of the match.

Australia had Sri Lanka three down after opener Usman Khawaja’s first double century and a ton on debut by Josh Inglis helped the tourists to 654-6 declared in the first match on Thursday. Sri Lanka were 44-3 by stumps on day two at Galle with senior batsmen Dinesh Chandimal,

With Australia in a commanding position during their opening innings against Sri Lanka, Inglis arrived at the crease with no intention of taking things slowly.

It was a debut three years in the making but Josh Inglis made it one to remember with a thrilling century against Sri Lanka to give Australia another selection headache in the lead-up to the World Test Championship.