The ailing world number one lost to Swiss Stanislas Wawrinka in Sunday's final, preventing the Spaniard drawing level on 14 grand slam singles titles with American Pete Sampras.
Nadal needed lengthy treatment at the start of the second set, hit back to win the third but Wawrinka eventually captured his debut slam with a 6-3 6-2 3-6 6-3 success.
His uncle told Cadena Ser's El Larguero show his nephew planned to return to his native Mallorca from Melbourne before heading to Argentina where he is due to take part in a clay event in Buenos Aires starting on February 10.
"The doctor said it's a tightening of the muscles and a few days rest should be enough," said Toni.
"He went into the match after feeling twinges during the week but very minor ones that normally do not affect you at all.
"In the second game of the second set he felt a pinch. When I asked him after treatment what was happening he said 'it's over'."
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- Pete Sampras
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