Rafael Nadal was knocked out of the Australian Open by American Mackenzie McDonald

The 22-time grand slam's wife, Maria Perello (left), watched as the Spaniard struggled on court

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She was visibly upset as the rest of his box was left shattered by Nadal's injury

World No 65 McDonald caused a huge upset at the Rod Laver Arena, winning in straight sets

Nadal struggled with a knock throughout, appearing to injure his left hip during the second set

The defeat will inevitably lead speculation over how much more Nadal's body will wish to take