Ireland beat Scotland 18-14, thanks in part to a brilliant length of the field intercept score from teenage wing Beibhinn Parsons.
Enormous credit is due to Scotland though, who came back from 13-0 down and who really ought to have gone ahead in the game after clawing it back to 13-7 only to see Parsons latch onto a pass just a metre from the try line.
Ireland were a threat from the off with No.8 Anna Caplice making a dart before full-back Lauren Delany was stopped just short of the try-line. Both of those players caught the eye for Ireland throughout alongside Ciara Griffin and hooker Cliodhna Maloney who were both excellent - but both forced off injured.
Scotland were penalised for not releasing on six minutes and fly-half Ellen Murphy kicked Ireland 3-0 in front.
Three minutes later Ireland extended their lead with a fine score.
Centre Michelle Claffey and Caplice moved the ball wide to hooker Moloney who beat wing Megan Gaffney with a show-and-go before holding off two tacklers to score in the corner - a brilliant finish for the front row player.
Scotland were coming under all sorts of pressure in the opening stages and Ireland scored another unconverted try on 15 minutes.
Griffin surged for the line after linking up with back-row colleague Edel McMahon before the ball was recycled and centre Sene Naoupu eased over.
Scotland’s first entry into the opposition’s 22 came on 24 minutes after a succession of penalties by Ireland only for the chance to be lost following an errant lineout. As the half wore on Scotland began to find their feet courtesy of their dominant scrum and Ireland’s rising penalty count.
Opting to kick for the corner rather than go for goal, Scotland’s persistence was rewarded with a try on the stroke of half-time.
After a mounting pressure inside the 22, centre Lisa Thomson slipped off a tackle and dotted down near the posts. Helen Nelson added the extras to close the gap to 13-7.
There was now little between the two sides as belief filled the away team.
Delany made a burst from deep at the start of the second period but Scotland responded with clean breaks from centre Hannah Smith and captain Rachel Malcolm.
The visitors were gaining in confidence as they put together some free-flowing moves with replacement fly-half Law pulling the strings.
Full-back Chloe Rollie almost produced a stunning score on the hour mark, beating several defenders after stealing the ball only to be brought down. Scotland were pushing hard as Nicole Cronin put her body on the line to stop Smith from touching down at the base of the post.
But Scotland were then hit with a sucker punch on 66 minutes.
With Scotland deep on attack Law’s pass was intercepted by Parsons who ran from just outside her side’s five-metre line to score. Parsons’ unconverted try gave her side a 18-7 advantage but Scotland refused to give in and made Ireland sweat.
The hosts were reduced to 14 players when replacement prop Leah Lyons saw yellow on 74 minutes before lock Wassell powered over.
Law landed the touchline conversion to set up a tense finale but Ireland hung on to get their campaign off to a winning start.
Scotland coach Phillip Doyle said: "We’re very proud of our players, we are very proud of the way we got ourselves back into that game. We knew Ireland were going to throw everything at it in the first 20 minutes and that’s exactly what happened, we weren’t meant to give away so many points in the first 20 but we eventually got ourselves into the game more and more which led to a lovely try straight off the training park. It shows the resilience of this team."
IRELAND WOMEN: Lauren Delany (Firwood Waterloo Ladies/IQ Rugby); Aoife Doyle (Railway Union/Munster), Sene Naoupu (Old Belvedere/Leinster), Michelle Claffey (Blackrock/Leinster), Beibhinn Parsons (Ballinasloe/Connacht); Ellen Murphy (Gloucester-Hartpury/IQ Rugby), Kathryn Dane (Old Belvedere/Ulster); Lindsay Peat (Railway Union/Leinster), Cliodhna Moloney (Wasps/IQ Rugby), Linda Djougang (Old Belvedere/Leinster), Aoife McDermott (Railway Union/Leinster), Nichola Fryday (Old Belvedere/Connacht), Ciara Griffin (UL Bohemians/Munster) (capt), Edel McMahon (Wasps/Connacht/IQ Rugby), Anna Caplice (Harlequins/IQ Rugby).
Replacements used: Victoria Dabanovich-O'Mahony (Old Belvedere/Leinster) for Moloney (27 mins), Dorothy Wall (Railway Union/Munster) for Griffin (half-time), Leah Lyons (Harlequins/IQ Rugby) for Djougang (55), Nicole Cronin (UL Bohemians/Munster) for Dane (56), Laura Feely (Galwegians/Connacht) for Peat (57), Ciara Cooney (Railway Union/Leinster) for McDermott, Claire Keohane (Railway Union/Munster) for Murphy (both 68), Djougang for McMahon (75). Not used: Laura Sheehan (UL Bohemians/Munster).
SCOTLAND WOMEN: Chloe Rollie (Harlequins); Rhona Lloyd (Loughborough Lightning), Hannah Smith (Watsonians), Lisa Thomson (Darlington Mowden Park), Megan Gaffney (Watsonians); Helen Nelson (Loughborough Lightning), Mairi McDonald (Hillhead Jordanhill); Leah Bartlett (Loughborough Lightning), Lana Skeldon (Darlington Mowden Park), Mairi Forsyth (Corstorphine Cougars), Emma Wassell (Corstorphine Cougars), Sarah Bonar (Loughborough Lightning), Rachel Malcolm (Loughborough Lightning) (capt), Rachel McLachlan (Darlington Mowden Park), Jade Konkel (Harlequins).
Replacements used: Sarah Law (Darlington Mowden Park) for Nelson (51 mins), Siobhan Cattigan (Stirling County) for McLachlan (56), Lisa Cockburn (Darlington Mowden Park) for Bartlett (62), Louise McMillan (Hillhead Jordanhill) for Malcolm (68), Evie Tonkin (Darlington Mowden Park) for Gaffney (70), Molly Wright (Watsonians) for Konkel (76). Not used: Panashe Muzambe (Edinburgh University/Watsonians), Alex Wallace (Harrogate RFC).
Referee: Aurélie Groizeleau (France)