Steph Catley's second-half penalty gave World Cup co-hosts Australia a 1-0 victory over debutants the Republic of Ireland in Sydney.
Catley, standing in as captain after Australia's star forward Sam Kerr suffered a calf injury on the eve of the game, converted the winner in the 52nd minute.
The Republic of Ireland frustrated the Matildas in the first half but their good work was undone when Marissa Sheva pushed Hayley Raso and Brazilian referee Edina Alves point to the spot.
Kerr, who is also set to miss Australia's second game with Nigeria, celebrated on the bench with her team-mates but was restrained as she nursed the injury which kept her out of her team's opener.
Megan Connolly, Katie McCabe and Louise Quinn all came close to what would have been a famous equaliser but the hosts held on to start their World Cup campaign with a win.
After co-hosts New Zealand stunned Norway in their opener, Australia were frustrated on home soil by the organised Irish defence.
Despite being disappointed at losing star player Kerr for their opening two games, the home fans produced an electric atmosphere at the soldout Stadium Australia.
While support from both sides got the party going, it was safe to say the match didn't carry the same gusto as the sturdy Republic defence frustrated Australia in a somewhat anti-climactic first-half.
Australia missed the focal point of the talismanic Kerr and struggled to create any clear-cut opportunities from open play, with their best chance of the half coming when Raso headed narrowly wide from a corner.
The Irish, who had just 29% possession in the first half, looked dangerous on the counter attack and McCabe's inch-perfect ball almost sent Kyra Carusa away, but the recovering Katrina Gorry managed to nip in and cut out the opening.
Vera Pauw had said pre-match that her plan was deeper than just dealing with Kerr, and her team looked solid. Caitlin Foord looked dangerous, but the forward was restricted to a weak shot into the side netting, and a missed opportunity when she failed to get a shot away before she was surrounded by green jerseys.
Gorry's weak long-range shot in injury-time summed up the frustration in the Australian camp as Pauw's defensive game plan worked to perfection in the opening 45 minutes.
After a tense start to their World Cup campaign, the goal immediately lifted the Matildas and Mary Fowler, who had impressed in bursts, fired over the top at the end of a charging run.
The impressive Gorry followed suit with a speculative effort before Pauw introduced teenager Abbie Larkin and Birmingham City's Lucy Quinn to try and find a way back into the game.
The substitutions lifted Ireland, and McCabe's corner almost deceived everyone before Denise O'Sullivan blazed over under pressure.
Heather Payne scuffed an effort from inside the area as the noise from the Irish section of the 75,784-strong crowd grew with each attack.
Despite the improvement, Australia came close to a second when Niamh Fahey threw herself in front of Foord's shot, and defensive partner Quinn did likewise to deny Kyra Cooney-Cross.
Australian hearts were in their mouths when Connolly's free-kick was deflected onto the roof of the net before McCabe forced a save from Mackenzie Arnold and Louise Quinn headed just wide, but the co-hosts secured the win despite the frantic finish.
Player of the match
McCabeKatie McCabe
Australia
Squad number9Player nameFoord
Squad number7Player nameCatley
Squad number21Player nameCarpenter
Squad number19Player nameGorry
Squad number18Player nameArnold
Squad number16Player nameRaso
Squad number10Player namevan Egmond
Squad number4Player namePolkinghorne
Squad number11Player nameFowler
Squad number5Player nameVine
Squad number14Player nameKennedy
Squad number23Player nameCooney-Cross
Squad number15Player nameHunt
Republic of Ireland
Squad number11Player nameMcCabe
Squad number4Player nameQuinn
Squad number10Player nameO'Sullivan
Squad number1Player nameBrosnan
Squad number15Player nameQuinn
Squad number14Player namePayne
Squad number6Player nameConnolly
Squad number19Player nameLarkin
Squad number18Player nameCarusa
Squad number5Player nameFahey
Squad number17Player nameFarrelly
Squad number20Player nameSheva
Squad number22Player nameAtkinson
Squad number8Player nameLittlejohn
Line-ups
Australia
Formation 4-4-2
18Arnold
21Carpenter15Hunt14Kennedy7Catley
16Raso19Gorry23Cooney-Cross5Vine
9Foord11Fowler
18Arnold21Carpenter15Hunt14Kennedy7Catley16Raso19Gorry23Cooney-Cross5VineSubstituted forvan Egmondat 75'minutes9Foord11FowlerSubstituted forPolkinghorneat 85'minutesSubstitutes
1Williams2Nevin3Luik4Polkinghorne6Wheeler8Chidiac10van Egmond12Micah13Yallop17Simon20Kerr22GrantIreland
Formation 3-4-3
1Brosnan
5Fahey4Quinn6Connolly
14Payne10O'Sullivan8Littlejohn11McCabe
17Farrelly18Carusa20Sheva
1Brosnan5Fahey4Quinn6Connolly14Payne10O'SullivanBooked at 41mins8Littlejohn11McCabe17FarrellySubstituted forLarkinat 63'minutes18CarusaSubstituted forAtkinsonat 87'minutes20ShevaSubstituted forQuinnat 63'minutesSubstitutes
2O'Riordan3Mustaki7Caldwell9Barrett12Agg13O'Gorman15Quinn16Moloney19Larkin21Grant22Atkinson23WalshReferee:Edina Alves BatistaAttendance:75,784Live Text
Match ends, Australia 1, Republic of Ireland Women 0.
Second Half ends, Australia 1, Republic of Ireland Women 0.
Attempt missed. Louise Quinn (Republic of Ireland Women) header from the centre of the box misses to the left. Assisted by Katie McCabe with a cross.
Attempt saved. Katie McCabe (Republic of Ireland Women) right footed shot from the centre of the box is saved in the bottom right corner. Assisted by Abbie Larkin.
Delay over. They are ready to continue.
Delay in match because of an injury Steph Catley (Australia).
Attempt missed. Abbie Larkin (Republic of Ireland Women) right footed shot from the right side of the box is too high following a set piece situation.
Foul by Katrina Gorry (Australia).
Katie McCabe (Republic of Ireland Women) wins a free kick in the attacking half.
Corner, Republic of Ireland Women. Conceded by Mackenzie Arnold.
Corner, Republic of Ireland Women. Conceded by Clare Polkinghorne.
Attempt blocked. Megan Connolly (Republic of Ireland Women) right footed shot from outside the box is blocked.
Foul by Clare Hunt (Australia).
Lucy Quinn (Republic of Ireland Women) wins a free kick in the attacking half.
Substitution, Republic of Ireland Women. Izzy Atkinson replaces Kyra Carusa.
Hayley Raso (Australia) wins a free kick in the attacking half.
Foul by Ruesha Littlejohn (Republic of Ireland Women).
Substitution, Australia. Clare Polkinghorne replaces Mary Fowler.
Corner, Republic of Ireland Women. Conceded by Alanna Kennedy.
Attempt blocked. Kyra Cooney-Cross (Australia) right footed shot from the left side of the box is blocked. Assisted by Emily van Egmond.