Medvedev
Nadal had to fight back from two sets down in their previous meeting in Melbourne in January to clinch a men's record 21st Grand Slam title.
A second triumph at Melbourne Park for 2009 champion Nadal will break a three-way tie for the most major titles in the men's game.
Federer will face a "reality check" when he returns to the Tour after a lengthy injury break, seven-time major champion Mats Wilander said.
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