PORTLAND, Ore. - Canadian teen star Brooke Henderson is one stroke off the lead after the opening round of the LPGA Tour's Cambia Portland Classic on Thursday.

The 17-year-old from Smiths Falls, Ont., birdied six of the first 13 holes for a 6-under 66. Henderson, who doesn't turn 18 until September, has made $466,818 in nine LPGA Tour tournaments this year. She earned a spot in the field in Monday qualifying, and thought that helped Thursday.

"I feel much more comfortable in the first round than I do a lot of times because I've already played this golf course in a competitive atmosphere this week," Henderson said.

Amy Anderson and Sandra Changkija shared the first-round lead at 7 under.

"I got off to a pretty fast start," Henderson said. "I was 4 under through the first nine, and really took advantage of the soft and scorable conditions out there this morning."

In warm, calm afternoon conditions, Anderson had five consecutive birdies on the front nine in her bogey-free round at Columbia Edgewater. Changkija, playing in the morning, made six birdies on her opening nine and reached 8 under before finishing with a bogey.

Anderson, the 23-year-old former North Dakota State player who won an NCAA-record 20 tournaments, had never led a round during her two-year LPGA Tour career. She's coming off her best finish of the year, a tie for eighth in Michigan at the Meijer LPGA Classic.

The 26-year-old Changkija, in her fourth LPGA season, has only two career top-10 finishes, but one came at the 2013 Portland stop. The 65 was her lowest competitive round since shooting 63 in Canada in the 2012 Manulife Financial Classic.

Alison Lee and Julieta Granada join Henderson at a shot back of the lead.

Mo Martin and Cristie Kerr shot 67. Second-ranked Lydia Ko opened with a 70, and No. 3 Stacy Lewis had a 71.

Defending champion Austin Ernst made four birdies and four bogeys and shot 72.

Suzann Pettersen, the Portland winner in 2011 and 2013, started her round with a double bogey and shot 75.

The Portland Classic is the penultimate tournament before the U.S. Solheim Cup team is set.

The top eight players in the Solheim Cup standings, the top two in the world ranking not among the top eight in the standings, and two captain's picks will make up the 12-player team for the Sept. 18-20 matches against Europe in Germany. Six players have clinched spots in the standings. No. 7 Angela Stanford shot 74, and No. 8 Gerina Piller had a 72.

Many players are wearing pins and ribbons honouring LPGA pioneer Louise Suggs, who died Friday at 91. Suggs, an 11-time major winner, was an LPGA founding member in 1950.

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With files from Nick Daschel of The Associated Press

News from © The Associated Press, 2015