'NO IDEA WHAT HAPPENED': CRAMPS HEADLINE BRAZIL, CHINA EPIC

Brazil's Beatriz Haddad Maia and China's Xinyu Gao played out an epic three-hour and 22-minute encounter at the United Cup despite the pair suffering from extreme cramps.

Gao, ranked No.175, caused an almighty upset to take down world No.17 Beatriz Haddad Maia 5-7 6-4 7-5 at Perth's RAC Arena last night.

The physical brutality of the match took its toll on Haddad Maia, who in the eighth game of the third set, was unable to move due to a severe cramp.

Visibly struggling, the physio could not treat the US Open quarter-finalist as the rules state that no player can use a medical timeout for cramps.

As a result, Haddad Maia was glued to the baseline — reaching the point where she had no other option but to serve underarm.

Yet she wasn't the only one experiencing pain as Gao reached down in agony on multiple occasions, seemingly fighting an issue with her heavily strapped leg, later admitting it was cramp.

"I have no idea what is [happening] right now. My brain was just empty, my whole body was cramping," an exhausted Gao said after the match.

China completed an impressive 3-0 sweep, as Zhang Zhizhen proved too strong for Thiago Monteiro in a 6-3 6-0 win before claiming another straight-sets victory in the mixed doubles.