OSAKA, Japan - All six first round matches at the HP Open on Monday were completed with straight sets efficiency, defending champion Tamarine Tanasugarn leading the way by dispatching up-and-coming US teenager Christina McHale, the No.8 seed.

Twelve months ago, Tanasugarn defeated Japanese heroine Kimiko Date-Krumm in the oldest known final ever played on the WTA, their combined ages tallying to 73 years. On Monday, the 34-year-old Thai veteran showed her determination to hold onto the trophy.

McHale broke in the second game for a 2-0 lead, but Tanasugarn won six of the next seven games to pocket the opener. The American again drew blood in the first game of the second set, but Tanasugarn broke right back in a nine-deuce game and, after the pair had exchanged breaks midway through the set, made the decisive breakthrough for a 63 75 win.

In other matches, No.7 seed Chanelle Scheepers continued her run of form in Asia with a 62 62 defeat of Alla Kudryavtseva; Mathilde Johansson beat feisty Irina Falconi; Eleni Daniilidou defeated Anastasia Pivovarova; and Misaki Doi waved the flag for the host nation by edging Coco Vandeweghe, 64 64. In the final contest of the day, French No.2 seed Marion Bartoli - who was upset by Tanasugarn in last year's semifinals - was too strong for Hungary's Melinda Czink, 62 62.

Japanese players Erika Sema and Shuko Aoyama won through to the main draw from qualifying, along with Thailand's Noppawan Lertcheewakarn and Yaroslava Shvedova of Kazakhstan. Lertcheewakarn and Aoyama earned their berths with grueling three set wins over Czech twins Kristyna and Karolina Pliskova respectively.

Lertcheewakarn faces top seed Samantha Stosur on Tuesday, with that match to be followed by Date-Krumm against fourth seed Petra Cetkovska.