The Hockeyroos had displayed plenty of attacking flair in opening their Olympic competition with respective 3-1 and 6-0 wins over Spain and China.

But Japan - the only side in Pool B without a point after losing twice - stood firm until Maddy Fitzpatrick's third-quarter strike broke the deadlock.

"I was really proud of the way the girls were patient," Bone said.

"Japan were really impressive in the first half and we didn't get many opportunities.

"We spoke about it at half-time, just to keep that patience.

"When we create opportunities we need to put them in.

"We're going to stick with our way of playing as we've been successful so far.

"I don't think need to change much. We need to keep on building game to game."

Japan, the lowest ranked team in the competition, almost took the lead through Kanon Mori during the early exchanges.

But Hockeyroos goalkeeper Rachael Lynch - winning her 230th cap - tipped her shot around the post.

Australia were nowhere near as clinical as they had been against Spain and China.

Kate Jenner had a penalty corner blocked and Brooke Peris struck a post.

Kaitlin Nobbs then saw her penalty stroke saved by outstanding Japan goalkeeper Sakiyo Asano.

There was a second-quarter scare for Australia as Yuri Nagai's powerful shot was disallowed.

But Fitzpatrick punished Japan after a penalty corner routine had almost broken down.

Coach Katrina Powell, part of the Hockeyroos' teams that won Olympic gold in 1996 and 2000, said: "It was not an easy win at all.

"We were expecting a very tough game because Japan are very well drilled, fit and high-pressing team.

"They gave us a lot of trouble and we are very pleased to come away with the three points."

Australia make a swift return to action against New Zealand on Thursday.

Australian Associated Press