Hewitt struggled with a string of unforced errors throughout

The number three seed, who knocked out Chela in an acrimonious tie in Melbourne a year ago, was some way off his best against the Argentine.

But there was no bad blood this time as he crumbled to a 6-4 6-4 6-7 (8-10) 6-2 loss, despite the support of the crowd.

In his defence, Hewitt had struggled with a left ankle injury throughout.

Chela, who also received treatment from the trainer for cramp in the fourth set, had earlier knocked out Briton Andy Murray in the first round.

The Argentine said: "I'm really happy - he's a big fighter and he showed that by winning the third set."

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Chela dominated the match throughout and comfortably held off an out-of-sorts Hewitt in the first set.

His rival, however, looked set to level proceedings in the second set when he moved to 3-1 but he was twice broken to lose the advantage and silence the crowd at the Rod Laver Arena.

It was virtually a mirror image in the third set as Hewitt went 3-0 up before being dragged back to a tie-break.

It was then, and only then, that the former world number one showed his best form, although it took him seven break points to take the set.

But that was where Hewitt's challenge effectively ended, as his ankle, which had to be treated by the trainer, clearly troubled him.