Ajla Tomljanovic has suffered an upset 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.