Carlota Ciganda and Gemma Dryburgh shared the clubhouse lead on four-under-par during Thursday's opening round of the Portland Classic. One-under after 12 holes, Spain's Ciganda birdie three of the next four on the way to her round of 68. Dryburgh had an eventful first round that included an eagle, three bogeys and five birdies - the last, at the 18th hole, giving the Scot a share of the clubhouse lead. Brooke Henderson of Canada started her bid for a third Portland Classic with a two-under-par round of 70.