Struggling Rafael Nadal beats plucky qualifier in five-set epic

Gushing sweat and stooping woozily between points, the sickly Spaniard dragged his cramping body into a fifth set under the lights of Rod Laver Arena, breaking the 112th-ranked American in the 11th game before closing out a win in four gruelling hours and 12 minutes.

Nadal slumped to his knees on the blue hard court having narrowly averted a repeat of his Melbourne Park jinx.

"It was a very tough night for me (and) ... a tough period of seven months without competition," Nadal, who was out of action for several months during the latter half of the 2014 season through injury and illness, said in a courtside interview.

"Today was a little bit humid conditions and I felt very tired after the first set, through the whole match.

"The fantastic crowd helped a lot so many thanks for that."

The third seed, still recovering from an injury-hit 2014, appeared in total control throughout the first set, needing just over 30 minutes to take the lead in the match.

However, with Nadal complaining of feeling dizzy, Smyczek looked to take his chances when they presented themselves and took advantage of a number of uncharacteristic errors from the Spaniard to pull level.

The third set continued to ebb and flow with both players unwilling to show weakness. Still struggling physically, Nadal did well to reach a tie-break, but was powerless as Smyczek bludgeoned his way into the lead for the first time in the match.

However, in typical fashion, Nadal showed incredible determination and grit; changing up his game in an almost all-or-nothing attempt to get back into the match. And it worked as he broke the American twice in the fourth set to take the contest into a decider.

And with just over four hours gone, Nadal claimed the decisive break in the 11th game of the set before serving out the match.

For much of the match, there was a hush over the terraces, with many in the crowd no doubt spooked by the memories of Nadal's torture in the final last year when he lost to Stan Wawrinka while carrying a back injury.

Nadal's coach and uncle Toni Nadal revealed his nephew had been bitten below the eye by a mosquito in the run up to the match, adding further intrigue to a day of high drama at Melbourne Park.