The 16-year-old, with her maiden title under her belt in the first leg last week, defeated Belgium's Catherine Grotz 6-3 6-2 in the first round on Wednesday.

Nungnadda, who joined Tamarine Tanasugarn and Suchanan Viratprasert as the youngest ITF winner from Thailand at 16 years of age, will next play Belgian second-seeded Davinia Lobbinger, who had a first-round bye.

The two played each other for the first time in the semi-final last week, with the Thai ending up the winner in three tough sets by 6-3 6-7 (8-10) 7-5.

In the doubles first round, Nungnadda and Christian Neves of Brazil blanked Bossy Grotz of Belgium and Usoegebu Akaegbusi of Nigeria 6-0 6-0.

In Cherbourg, France, Davis Cup doubles pair Sonchat and Sanchai Ratiwatana beat Guillaume Legat and Trystan Meniane of France 6-4 6-3 to reach the semi-finals of the $50,000 Challenger Ford De Cherbourg on Wednesday.

Meanwhile, seeded players stormed into the quarter-finals of the Bt1-million National Tennis Championships, which got under way at the Rama Gardens Hotel in Bangkok yesterday.

On the men's side, SEA Games national player and top seed Weerapat Dokmaiklee survived a scare from young rival Palanupap Pulanawit before summoning all his experience to win the third-round match 6-2 5-7 7-6 (7-4).

Second-seed Kirati Siributwong had a much easier time against Suthikorn Aparnukul as he won 6-1 6-1.