Tomljanovic upset by Ahn in WTA event

Ajla Tomljanovic has suffered a surprise loss to American qualifier Kristie Ahn in the first round of the WTA's Silicon Valley Classic.

The 26-year-old Tomljanovic went down to world No.178 Anh 6-3 4-6 6-4 in San Jose, in a see-sawing contest in which both players struggled to hold serve.

After reaching a career high of world No.39 in April, Tomljanovic will drop to at least 44th when the updated rankings are released on Monday.

Former San Jose finalist Maria Sakkari got off to a strong start to this year's campaign with a 6-1 6-4 victory over Ekaterina Alexandrova.

Greek seventh seed Sakkari will face Mayo Hibi in the next round after the Japanese defeated fellow qualifier Timea Babos 6-2 3-6 7-6 (7-3).

In the day's early match, sixth seeded Spaniard Carla Suarez Navarro accounted for Magda Linette 6-3 6-3.