Second seed Rafael Nadal ground down German Philipp Kohlschreiber to win a tough match 7-5, 6-3, 4-6, 6-2 in the Australian Open second round on Thursday.

Nadal was forced to work extremely hard by the 23-year-old world number 61, who slugged it out with the Spaniard in the late match on Rod Laver Arena which finished at 0130 local time.

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Nadal, seeking a first Australian Open title, looked to be heading for a quick victory at two sets up but Kohlschreiber used his superb forehand to great effect to take the third set as both players struggled to hold serve.

Nadal, French Open champion in 2005 and 2006, raced into a 4-0 lead in the fourth but Kohlschreiber still refused to lie down, clawing back two games before the Spaniard sealed victory on his second match point in three and a half hours.

Nadal will play Switzerland's Stanislas Wawrinka, the number 31 seed, in the third round.