Spain's Rafael Nadal hits a return against Michael Mmoh of the US during their men's singles match on day four of the Australian Open tennis tournament in Melbourne on Feb 11, 2021. (BRANDON MALONE / AFP)

MELBOURNE - Rafa Nadal dispelled any remaining doubts over his fitness with a commanding 6-1 6-4 6-2 win against American qualifier Michael Mmoh on Thursday to march into the Australian Open third round and stay on track for a record 21st Grand Slam title.

Rafa Nadal will next meet either Briton Cameron Norrie or Russian qualifier Roman Safiullin

The second seed did not play a match in Spain’s ATP Cup campaign last week with a back problem and following his opening win in Melbourne he had said the injury was still bothering him.

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Nadal showed no sign of discomfort, however, against the 177th-ranked American under the closed roof of the Rod Laver Arena and peppered the blue court with winners from both forehand and backhand sides as Mmoh watched on helplessly.

The 2009 Melbourne Park winner, who is tied with Roger Federer at 20 Grand Slam singles titles, will next meet either Briton Cameron Norrie or Russian qualifier Roman Safiullin.