Wawrinka, a grand slam champion in each of the last three years and the winner at Melbourne Park in 2014, was heading for a shock early exit when he dropped serve at 3-3 in the fifth set against Klizan.

However, the Slovakian threw away a 40-15 lead to immediately give the break back, before dropping serve again to hand Wawrinka a 4-6 6-4 7-5 4-6 6-4 victory.

"It was a tough one, for sure. But I'm really happy to get through in five sets," said the fourth seed, who has never lost a first-round match at the year's opening grand slam.

"It wasn't my best tennis, but I was fighting a lot.

"For sure it's a big relief, especially when you're a break down in the fifth, 4-3, 40-15."

There was a painful moment towards the end of the match when Wawrinka smashed a shot into Klizan's groin, the ball taking a deflection off the underdog's racket that could have prevented greater damage.

Wawrinka crossed the net to check on the well-being of his opponent and said in his news conference: "That was, for sure, a tough shot for him. 

"I'm sorry I touch him in the wrong place. But I think it was okay at the end. I just wanted to make sure he was okay."