Misfiring Stefanos Tsitsipas survived a thorough examination by former world number one junior Sebastian Baez before taking his place in the third round of the Australian Open on Thursday.

The Greek world number four raced through a first-set tie breaker but struggled to put away the tigerish 88th-ranked Argentine before winning in four sets.

Tsitsipas wrapped up the match 7-6 (7/1), 6-7 (5/7), 6-3, 6-4 in 3hr 22min on Margaret Court Arena and will next face Frenchman Benoit Paire.

"It wasn't easy. I'm glad I overcame that obstacle today. Lots of fighting, a little bit of swearing, but I'm glad to be in the third round," Tsitsipas, who is yet to win a Grand Slam, said.

"It was a pretty hot day today playing here, but I tried to play with the heart and it paid out at the end." 

Tsitsipas, a two-time semi-finalist in Melbourne, struggled for fluency and was often cussing and frustrated by his mistiming off the racquet among his flurry of 63 unforced errors.

"I feel like I'm getting physically better in every single one of my matches," Tsitsipas said.

"My elbow hasn't been bothering me since Sydney. I see a very good progression since then, and I'm happy to be able to play that way."

Tsitsipas had break points in Baez's first two service games, but did not convert any of them.

Baez struck first, breaking the Greek in the ninth game when Tsitsipas's forehand was wide.

Tsitsipas broke back straight away and steamed away in the tiebreaker with three mini-breaks, mixed up with some wonderful backhands and bullet precision serving.

The second set went to another tiebreaker and Tsitsipas worked his way to a 5-3 lead only for Baez to string together the next five points and level the match with a forehand winner.

Tsitsipas rattled through a double break to sprint to a 5-0 lead in the third set, but struggled to see it out, getting broken after holding three set points.

He finally claimed the set on his fourth set point but was having trouble with timing off the racquet.

Tsitsipas again stepped it up in the fourth set with an early break.

Tsitsipas became the first Greek player to reach a Grand Slam final when he lost to Novak Djokovic in last year's French Open final after leading by two sets.

He also holds the distinction of beating both Rafael Nadal and Roger Federer on his way to his semi-final appearances at the Australian Open.