'What is going on': Coach storms off in 'unbelievable' Aus Open drama

Daniil Medvedev's coach walked out on the Russian tennis star in the middle of his bad-tempered third round clash at the Australian Open on Saturday.

Medvedev extended his winning streak to 17 matches with a hard-earned 6-3 6-3 4-6 3-6 6-0 victory over Serbian Filip Krajinovic on Rod Laver Arena.

IN TEARS: Aus Open star breaks down in 'emotional' scenes

'WHAT IN THE WORLD': Shock over 'horrendous' Aus Open moment

'SAD': Novak Djokovic's shock announcement at Aus Open

The World No.4's win was far from straightforward, however, with a mid-match meltdown threatening to derail his tournament.

After comfortably taking the opening two sets against his Serbian opponent, things began to quickly unravel for the Russian.

Medvedev could be heard berating his coach Gilles Cervara in French after losing the third set to give Krajinovic a sniff of hope in the contest.

Medvedev reportedly yelled at Cervara to “just let me play” and to be quiet.

His mood only worsened as the Serb jumped out to an early advantage in the fourth set, with the drama far from over.

Still copping verbal sprays from Medvedev in Russian, French and English, the World No.4's coach decided he'd had enough and walked out in the middle of the fourth set.

“He got his bag, packed up and walked out of the stadium,” Jim Courier observed on Channel Nine.

Viewers were left baffled by the extraordinary scenes unfolding on Rod Laver Arena.

Russian star overcomes meltdown

Medvedev then took a medical timeout with his opponent 5-2 up before returning to see Krajinovic send the match into a deciding fifth set.

Things looked particularly bleak for the Russian, who had never won a five-set match in six previous attempts.

Incredibly though, it was one-way traffic in a lopsided final set as Medvedev finally regained his composure to stem the bleeding.

The 25-year-old steamrolled Krajinovic in the deciding set, somehow managing to not drop a game as he booked his place in the fourth round.

The charismatic but often volatile star cheekily claimed in his post-match interview that his coach left after knowing that the Russian was going to win.

“He said just before leaving that he was sure I was gonna win the match but he was gonna leave me alone to be more calm actually,” he told reporters.

“I won’t tell more because that was a good thing to do and luckily I won.”

Medvedev will now face Mackenzie McDonald for a sport in the quarter-finals.

Click here to sign up to our newsletter for all the latest and breaking stories from Australia and around the world.