STAN Wawrinka was expected to cruise past Martin Klizan, but the No. 4 seed found his assignment much tougher than he hoped.
He was up two-sets-to-one but the Slovakian hit back by taking the fourth to force the match into a decider.
The fifth set was a close affair, but Wawrinka - a three-time grand slam winner - was ultimately too good, closing it out 4-6 6-4 7-5 4-6 6-4.
However, his match was marred by an incident late in the final set.
The former Australian Open champion was booed by the crowd on Rod Laver Arena over a nasty incident that left his opponent Klizan keeled over.
In the thrilling and see-sawing five-setter, Wawrinka was jeered by the Melbourne crowd after he smacked a forehand smash straight into his opponent's groin at point blank range.
In a tense fifth set, Klizan lobbed a gentle half volley straight to Wawrinka for an easy mid-court put-away and walked aimlessly towards the net without even trying to put himself in a position to return Wawrinka's shot.
Instead, the No. 4 seed cracked his shot straight at Klizan, sparking brief boos from the crowd as the world No. 34 hunched over from the impact of the ball hitting him in his groin.
Wawrinka immediately jumped the net to check on his opponent's condition.
"Goodness me," a Channel 7 commentator said of Wawrinka's hit.
"It's one of those things, Wawrinka would expect Klizan to go left or right and decided to go up the middle not recognising that Klizan had given the point away. He was standing motionless. He's given up on the point and doesn't expect the ball to come his way. That would have hurt."
In Wawrinka’s defense, he couldn’t have known that Klizan would just go total sitting duck there. Assumed he’d move one way or the other. https://t.co/PvUoDY2yiB— Bill Connelly (@SBN_BillC) January 16, 2017
Ouch! Wawrinka thumps a ball at Klizan's groin - that's got to hurt! #AusOpen— George Bellshaw (@BellshawGeorge) January 16, 2017
That Wawrinka shot hit Klizan's racket. No way he would still be standing if it made contact with......— Stuart Fraser (@stu_fraser) January 16, 2017
Klizan appeared to suggest Wawrinka had targeted him on purpose, but stopped short of directly accusing him of deliberate foul play.
"I stopped playing. He could play anywhere. He had the whole court and he hit me so I don't know," he said.
"I have no comment for this. He could have played anywhere on court, but he hit me. I stopped. I was standing. I don't care. It's a game. It's sport. He hit me. It's OK. Nothing to do. I don't care."
Elsewhere, Belgian Steve Darcis ousted Australian Sam Groth in four sets 3-6 6-3 6-2 6-2. Darcis made just 15 unforced errors and hit 27 winners to claim the opening-round victory.
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