PORTLAND, Ore. — Brooke Henderson gave herself some breathing room in her bid for a breakthrough victory. The 17-year-old Canadian opened a five-stroke lead Saturday in the Portland Classic, shooting 7-under 65 at Columbia Edgewater for an 18-under 198 total. "I'm really happy to get it to (18 under), and hopefully (today) just improve on that just a little bit," Henderson, the second-round leader, said. She's trying to join Lydia Ko and Lexi Thompson as the only players to win an LPGA Tour title before turning 18. She tied the tournament 54-hole record set by Yani Tseng in 2013. The five-stroke margin is the largest third-round lead on the tour this year. Morgan Pressel (65) was second. Sandra Gal (65) and Caroline Masson (70) were at 12 under.