Tennys Sandgren. Pic/AFP

Unheralded American Tennys Sandgren upset Austria's fifth seed Dominic Thiem over five sets to advance to the quarter-finals of the Australian Open yesterday. The 97th-ranked Sandgren won 6-2, 4-6, 7-6 (7/4), 6-7 (7/9), 6-3 in just under four hours to continue his extraordinary run and will face Chung Hyeon in the last eight. Sandgren becomes just the second man in the last 20 years since Frenchman Nicolas Escude to make the quarter-finals on his Australian Open debut. He missed out on qualifying in the last four years to reach the main draw in Melbourne.