Steve Smith accepted his side had been outplayed in all three Tests against Sri Lanka after Rangana Herath and Dilruwan Perera bowled Australia out for 160 on Wednesday to seal a series sweep.
Australia had been in a strong position in the final Test, but lost five wickets for 23 runs shortly after lunch to collapse to a series whitewash defeat for their fourth successive tour of Asia.
Smith defended Australia's preparation for the series, which included just one warm-up match before the Tests began, while paying credit to Sri Lanka for their victory.
"It's been a tough series," Smith said. "We've been outplayed in all three matches.
"Sri Lanka have played great cricket, it's disappointing but it's a great learning curve for the guys.
"I don't think we can fault our preparation. We got here early and worked hard.
"In the first [Test] match, 117 all out in the first innings, we didn't get a chance to get in front of the game. Since then it's all come downhill, we've been outplayed in all facets, credit to Sri Lanka."
Smith, who believes Australia will have more about them in their upcoming ODI series against Sri Lanka, apologised to the travelling supporters for the whitewash.
"It's a different format, we've some new guys coming in," Smith said.
"The Test guys are going to be pretty flat after the last few weeks but we've got to be able to turn it around and hopefully we can be a bit more competitive in that format.
"Thank you to all the Australian supporters for coming over here. Apologies for what we have done, it's not been good enough."