Canadian teen Brooke Henderson opened a five-stroke lead Saturday in the Cambia Portland Classic, shooting a 7-under 65 at Columbia Edgewater.
The 17-year-old Henderson is trying to join Lydia Ko and Lexi Thompson as the only players to win an LPGA Tour title before turning 18.
On a warm, calm day, Henderson made seven birdies in her bogey-free round. Henderson, who turns 18 in September, tied the tournament 54-hole record of 18-under 198 set by Yani Tseng in 2013.
Morgan Pressel was second after a 65.
Henderson also had the 54-hole lead in April in California in the Swinging Skirts LPGA Classic. She closed with a 74 and end up finishing third.
The Canadian won the Symetra Tour's Four Winds Invitational in June in Indiana, and tied for fifth in the Women's PGA Championship — the second of the LPGA Tour's five majors.
A win Sunday would assure Henderson of finishing among the tour's top 40 on the money list, giving her an LPGA Tour card for next season. Through nine LPGA Tour tournaments, Henderson has banked $466,818.
LPGA Tour Commissioner Mike Whan denied Henderson's age petition last year, preventing her from playing Q-school. She earned a spot in the Portland Classic field in Monday qualifying.
Henderson is attempting to become the second Monday qualifier to win an LPGA Tour tournament. The only player to accomplish the feat was Laurel Keen in 2000.
Henderson took a one-stroke lead over Masson into the day. After the two matched birdies at the par-4 first, Henderson increased her lead to two strokes with a birdie at the par-3 second. Masson closed within a stroke with a birdie at the par-5 fifth, and both players birdied the par-5 seventh.
Henderson pulled away on the back nine, starting with birdies on the par-5 10th and par-4 11th.
Masson bogeyed the par-5 12th, giving Henderson a four-stroke lead. Even though Pressel birdied three of her final four holes, Henderson increased her lead to five strokes with birdies at the par-4 15th and par-3 16th.
German players Sandra Gal (65) and Caroline Masson (70) were tied for third 12 under.
Jaye Marie Green had a 63 — the best round of the week — to move into a tie for ninth at 9 under. Ko was tied for 53rd after 2 under after a 72.