'Got to call a spade a spade': Stefanos Tsitsipas slammed for 'cheap' loss to Aleksander Vukic

Australian star Aleksander Vukic has produced a brilliant straight-sets win over Stefanos Tsitsipas in the first round of the Adelaide International.

The 29-year-old was fired up on Centre Court on Tuesday night as he outlasted the former Australian Open and French Open finalist 7-6(7-3), 7-6(7-5).

Vukic roared as the final shot from the current world No.33 Tsitsipas rocketed into the net, sealing the upset as the crowd erupted with cheers.

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The seasoned Aussie took out the first-set tie-breaker with ease and the second set was just as evenly fought between the two spirited rivals.

At one stage, Tsitsipas was clearly struggling with the Aussie conditions when he had to swat some flies away from his face at 3-3 and on serve.

The popular Greek star had a wry smile on his face as the crowd laughed at the insects causing him some dramas, before swiftly getting back to his serve.

Tsitsipas managed to compose himself and was going game-for-game with Vukic throughout the second set, again sending it to a tie-breaker.

Vukic - who is more than 50 spots lower on the ATP rankings than Tsitsipas - was also producing some tremendous tennis, nailing world-class winners to test his rival.

"He looks really composed, don't see any sign of nerves - he hasn't been daunted by this court or this player whatsoever," John Millman said on commentary for Nine.

Tsitsipas took an early 3-1 lead and had a mini break, but started to falter, earning some criticism for his "cheap" strokes, including an ill-fated drop shot.

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"I don't understand his shot selection at all," Millman said.

"He's got the mini break, he had a slightly better than neutral exchange there and it was really poorly executed. You can't be giving away cheap points.

"We've got to call a spade a spade - two really poor points. A real let-off for Vukic."

The lapses in concentration and poor shot selection allowed Vukic to storm back and win the tie-breaker, the set and match in one fell swoop.

Asked post-match if defeating the former world No.3 was among the most satisfying results of his career, Vukic couldn't hide his excitement.

"I think in probably the last year, it was," the 87th-ranked male player said.

"I felt like in the last few months of last year, I started to play better and getting close to the likes of [Taylor] Fritz and [Casper] Ruud, but not beating the top-echelon players.

"I wanted to give it another crack today and I was happy that I kept my composure."