The tournament holders and world number one side were upset by India in their opening Group A contest and knew that anything other than victory today would leave them on the brink of a shock elimination.

They did things the hard way at the WACA Ground despite restricting Sri Lanka to 122-6 after the Asian side won the toss and opted to bat.

In response, the hosts slumped to 10-3 but Rachael Haynes scored 60 as she led the recovery alongside captain Meg Lanning.

The skipper ended unbeaten on 41 as the four-time champions got home with three balls to spare.

Sri Lankan captain Chamari Atapattu scored 50 in their innings before falling to Nicola Carey, who was the pick of the home bowlers after taking 2-18.

This put the brakes on hopes of a large total as only 31 runs were added in the final six overs.

However, the score suddenly seemed to be good enough when Alyssa Healey was bowled by Udeshika Prabodhani for a duck just two balls into the reply.

Prabodhani then bowled Ashleigh Gardner as well and when Beth Mooney was stumped by Anushka Sanjeewan off the bowling of Shashikala Siriwardene, Australia were in huge trouble.

Haynes and Lanning produced a partnership of 95 to turn the game around, with the former blasting four fours and two sixes.

Sri Lanka, who have now lost both of their matches, were left to rue sloppy fielding, which included three dropped catches, and a wasted umpire review from Atapattu.

This left them without one when Lanning was wrongly given not out on 15, despite edging a catch behind.

"We just needed to build a partnership and get the scorecard moving a little bit," said Lanning. 

"Luckily we were only chasing 120 so it sort of allows a little bit of time to get into it. 

"It's certainly a nicer feeling to have the win on the board. 

"We would have liked to have played better and we definitely need to improve heading into the next couple of games but sometimes it's just nice to get off the mark. 

"I thought our bowling was really good today, our fielding was good, just a little bit of an unsettling start with the bat." 

India remain in control of the group after they beat Bangladesh by 18 runs to record their second victory.

After being asked to bat, India's Shafali Verma scored 39 and Jemimah Rodrigues 34 in their total of 142-6.

Bangladesh, who were playing their opening game, fell short in the chase and ended on 124-8, with Poonam Yadav ending with figures of 3-18.

After a rest day tomorrow, the tournament will return on Wednesday (February 26) with two matches in Group B.

England will hope to recover from their opening defeat to South Africa against tournament underdogs Thailand, while Pakistan will open their World Cup against West Indies, who beat the Thais first up.

Both games will be played at the Manuka Oval in Canberra.

The top two sides from each group will reach the semi-finals.