The world No 32 hit all 18 greens in regulation, picking up birdies at the par-five first, sixth and 17th holes on the O’Meara Course to share seventh place on three-under.
While she was frustrated to take 34 putts, she was just two strokes behind Italy’s Alessandra Fanali, Finland’s Ursula Wikstrom and Spain’s Luna Sobron Galmes, who posted 68s to head France’s Pauline Roussin-Bouchard, Germany’s Carolin Kauffmann and France’s Agathe Sauzon by a shot. Roscommon amateur Olivia Costello (16) continued her brilliant run of recent form by carding a two-under 71 to share 17th place.
But Mehaffey, who returns to the fairways this week after taking a 10-week break to look after her mental health, was arguably as impressive as Maguire and Costello, carding a one-under 72 to share 29th with the impressive Edmondstown amateur Anna Abom (18).
“Olivia is a good friend of mine for a long time,” Maguire said with a big grin. “We’re going to Coldplay on Monday night together – the better form we’re all in, the better!
“She’s been through a lot. She’s a fantastic player and an even better person, so nice to see her under par.”
As for her own round, Maguire felt she might have been seven-under on the front nine alone, so well did she hit the ball from tee to green.
“It was steady,” she said. “Gave myself a lot of chances. Felt like I hit some really good putts on the front nine, just burned the edge quite a few times but tried to stay patient. There were a lot of chances, but the pins were on tricky little slopes, and it seemed like I had a lot of putts that just snapped one way or the other. Happy with how I hit it. Gave myself chances. It’s just a case of sinking a few more putts over the next few days.”
Mehaffey made three birdies in her 72 and walked away pleased with her start after her long break.
“I said to my caddie, ‘I haven’t had as much fun on the golf course in a long time’, so it was really enjoyable,” the Co Armagh star said.
While Kildare’s Lauren Walsh shot 74 to share 60th with Annabel Wilson, amateurs Kate Dillon and Roisin Scanlon, Costello (16) was impressive.
After helping Great Britain and Ireland win the Junior Vagliano Trophy for the first time last week, she rode that wave of confidence into Carton House for what is her third Irish Open appearance.
“Yeah, huge,” she said after finishing with a birdie for her 71. “To be the first GB&I team to win is a good lesson coming into the week; it was a big confidence boost coming in.”
As for Abom, she was thrilled to take advantage of a late call-up for her Irish Open debut.
“Obviously to play well is just a bonus,” she said. “I’m really just here to enjoy the experience and learn as much as I can.”
After seeing Beth Coulter, Sara Byrne and Aine Donegan compete well at Dromoland Castle last year, she’ll be pulling for the Irish trio in the Curtis Cup, which begins at Sunningdale today.
While the Rhodes sisters Patience and Mimi take on Melanie Green and Rachel Keuhn in the opening foursomes, Donegan and Coulter are paired together against Jasmine Koo and Zoe Campos as Byrne partners world number one Lottie Woad against Catherine Park and Asterisk Talley. In the Betfred British Masters at the Belfry, Simon Thornton’s level-par 72 left him tied for 42nd, five shots behind Jeong weon Ko and Paul Waring, but Tom McKibbin has work to do to make the cut after a two-over 74.
Meanwhile, Jens Fahrbring and Alexander Levy opened with seven-under 63s to take a two-stroke lead in the Rosa Challenge Tour in Poland.
Ballymena’s Dermot McElroy fired a bogey-free 66 to share seventh with Conor Purcell 28th after a 68.
At the first stage of the DP World Tour Q-School, Rowan Lester shot a two-under 68 to go into the final round just a shot outside the qualifying places on one-over par at the Players Club in Bristol.
British Masters, 12.30pm
Tour Champship, 6.0pm
(All Sky Sports)
Women’s Irish Open, 4.0pm
(Sky Sports+)