Ireland's Rebecca Coakley carded a course record-equalling nine-under-par 63 to claim a four-shot lead at the Deutsche Bank Ladies Swiss Open at Golf Gerre Losone.
The Carlow 27-year-old's score - which included an eagle, eight birdies and only one bogey - matched that of France's Gwladys Nocera in 2006 and put her well ahead of a group on five under.
Starting at the 10th, she began with a birdie, holed a 101-yard pitching wedge approach at the par-four 12th before birdies at 13 and 14 took her to the turn in five under.
The former Irish amateur champion picked up another shot at the second before she finished with four birdies and that solitary bogey in her final five holes.
"I had 22 putts. When you hole out with a pitching wedge and putt in from off the green on nine it makes life easy," said Coakley.
"Today feels great and we will see what tomorrow will bring. If it happens, it happens. If not, it's not the end of the world.
"I'm going through a few changes at the moment so I've got to keep at it.
"Some weeks are going to be harder than others. If I can stick to it then hopefully there will be more of this.
"Tomorrow I'm going to do exactly the same."
England's Lisa Hall shot a five-under 67 to earn a share of second with playing partners Suzann Pettersen and Amy Yang, Ludivine Kreutz, Paula Marti, Marina Arruti and Swiss amateur Anais Maggetti.
"It was nice playing with Suzann and Amy and we all ended up shooting five-under but in different ways," said Hall.
"I actually had seven birdies and two bogeys and I look forward to playing with them again tomorrow and having another shoot-out."
England's Laura Davies is two shots further back in a share of 13th.
Collated first-round scores (Par 72):
63 Rebecca Coakley (Irl)
67 Marina Arruti (Spa), Ludivine Kreutz (Fra), Suzann Pettersen (Nor), Lisa Hall (Eng), Amy Yang (Kor), Paula Marti (Spa), Anais Maggetti (Swi)
68 Nikki Garrett (Aus), Ursula Wikstrom (Fin), Nicole Gergely (Aut), Ana B Sanchez (Spa)
69 Veronica Zorzi (Ita), Iben Tinning (Den), Marjet Van Der Graaff (Ned), Georgina Simpson (Eng), Laura Davies (Eng), Kirsty S Taylor (Eng), Katharina Schallenberg (Ger)
70 Rebecca Huber (Swi), Dana Lacey (Aus), Rebecca Hudson (Eng), Bronwyn Mullins-Lane (Aus), Lydia Hall (Wal), Laurette Maritz (Rsa), Kiran Matharu (Eng), Sophie Sandolo (Ita), Anja Monke (Ger), Gwladys Nocera (Fra), Anna Tybring (Swe), Maria Verchenova (Rus)
71 Caroline Rominger (Swi), Vittoria Valvassori (Ita), Natalie Claire Booth (Eng), Nathalie David-Mila (Fra), Emma Cabrera-Bello (Spa), Melissa Reid (Eng), Felicity Johnson (Eng), Marianne Skarpnord (Nor), Samantha Head (Eng), Anne-Lise Caudal (Fra), Rachel Bell (Eng), Lee-Anne Pace (Rsa), Amanda Moltke-Leth (Den), Marta Prieto (Spa), Lynn Kenny (Sco), Martina Eberl (Ger), Becky Brewerton (Wal), Lotta Wahlin (Swe), Ellen Smets (Bel)
72 Laura Terebey (USA), Laura Cabanillas (Spa), Johanna Westerberg (Swe), Cecilia Ekelundh (Swe), Fame More (Eng), Caroline Afonso (Fra), Bettina Hauert (Ger), Titiya Plucksataporn (Tha), Joanne Mills (Aus), Tania Elosegui (Spa)
73 Mianne Bagger (Den), Mette Buus (Den), Natascha Fink (Aut), Ana Larraneta (Spa), Asa Gottmo (Swe), Federica Piovano (Ita), Diana Luna (Ita), Lynn Brooky (Nzl), Isabella Maconi (Ita), Kate Combes (Aus), Stefanie Michl (Aut), Elin Ohlsson (Swe), Karen-Margrethe Juul (Den), Jade Schaeffer (Fra), Clare Queen (Sco), Henrietta Zuel (Eng), Denise-Charlotte Becker (Ger)
74 Stefania Croce (Ita), Stephanie Arricau (Fra), Lisa Holm Sorensen (Den), Martina Gillen (Irl), Itziar Elguezabal (Spa), Jenna Wilson (Sco), Eva Steinberger (Aut), Anna Knutsson (Swe), Emma Zackrisson (Swe), Trish Johnson (Eng), Anna Rossi (Ita), Julie Greciet (Fra)
75 Danielle Masters (Eng), Stacy Lee Bregman (Rsa), Lara Tadiotto (Bel), Kaisa Ruuttila (Fin), Jehanne Jail (Fra), Anne Norman Hansen (Den), Lora Fairclough (Eng), Karen Lunn (Aus), Joanne Morley (Eng), Florence Luscher (Swi)
76 Olof Maria Jonsdottir (Ice), Eleanor Pilgrim (Wal), Sara Beautell (Spa), Cherie Byrnes (Aus), Melodie Bourdy (Fra), Elisabeth Esterl (Ger), Maria Boden (Swe), Beatriz Recari (Spa), Elizabeth Mckinnon (Nzl), Frederique Seeholzer (Swi), Lill Kristin Saether (Nor), Nora Angehrn (Swi), Sophie Walker (Eng)
77 Christine Hallstrom (Swe), Margherita Rigon (Ita), Leah Hart (Aus), Fanny Vuignier (Swi)
78 Cassandra Kirkland (Fra), Kathryn Imrie (Sco), Frances Bondad (Aus), Julie Tvede (Den)
79 Camille Fallay (Fra)
80 Jo Clingan (Eng)
81 Rui Yokomine (Jpn)
83 Denise Simon (Ger), Xonia Wunsch (Spa), Sofia Renell (Swe)
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