Furious Carreno Busta and Zverev bow out, Djokovic marches on

Pablo Carreno Busta apologised after reacting furiously to his defeat to Kei Nishikori at the Australian Open, while Alexander Zverev also lost his cool as he was dumped out on Monday too.

Tensions were running high on the first day of the second week at Melbourne Park, where history-chasing world number one Novak Djokovic moved into the quarter-finals.

While Djokovic - aiming to become the first man to win the tournament for a seventh time - was on his way to beating Daniil Medvedev 6-4 6-7 (5-7) 6-2 6-3 on Rod Laver Arena, the real drama was unfolding on Margaret Court Arena.

Carreno Busta was livid when the chair umpire refused to replay a point awarded to Nishikori in a final-set tie-break, which the Spaniard led 8-5 at the time, and he failed to regain his composure as the eighth seed came from two sets down to advance.

A seething Carreno Busta threw his bag down and vented his fury at the chair umpire as he made his way off court, while Zverev had a meltdown in his straight-sets loss to Milos Raonic.

Lucas Pouille continued his stunning run, coming from a set down to oust 11th seed Borna Coric.

Simply...unbelievable. From 0-2 sets down, an exhausted @keinishikori fights back to def. Carreño Busta 6-7(8) 4-6 7-6(4) 6-4 7-6(8) in 5 hours and 5 minutes.#AusOpen pic.twitter.com/3WUAq1Japx

— #AusOpen (@AustralianOpen) January 21, 2019

CARRENO BUSTA SORRY FOR EXPLOSIVE EXIT

There had already been plenty of action to keep the crowd on the edge of their seats in a thrilling contest between Carreno Busta and Nishikori, which took five hours and five minutes to settle.

Nishikori came from two sets down for the second time in the tournament and came through a third five-set match to set up an encounter with Djokovic, having failed to serve out the match when leading 5-4 in the decider.

Carreno Busta was two points away from going through in the decisive breaker, but lost his head after his shot hit the net cord and was called out despite striking the line, with Nishikori putting away a winner.

The 23rd seed challenged and although Hawkeye showed the ball was in, the chair umpire refused to play the point again as he said the line judge called out after Nishikori won the point.

Carreno Busta argued over the decision at length and was booed off court as he continued to unleash verbal volleys, but stated in his media conference: "Obviously I'm very sad, because after five hours fighting, the way that I left from the court wasn't correct, and I'm so sorry. That is not me."

ZVEREV MAJOR WOES CONTINUE

Zverev also felt the heat on the big stage once again, suffering a 6-1 6-1 7-6 (7-5) defeat to big-serving Canadian Raonic.

The ATP Finals champion has reached just one major quarter-final - at the French Open last year - and his frustration boiled over in an emphatic defeat on Rod Laver Arena.

Zverev thrashed his racket into the hard court nine times as he sat in his chair after going 4-1 down in the second set and could not turn the tide with a replacement in hand.

"Yeah, it made me feel better. I was very angry, so I let my anger out," the German said after his latest setback.

Frustration level #AusOpen pic.twitter.com/7ThmuvoRzo

— #AusOpen (@AustralianOpen) January 21, 2019

POUILLE THRIVING WITH MAURESMO IN HIS CORNER

While Zverev reflected on falling short again, Pouille defied the odds to take his place in the last eight.

The 28th seed from France had lost all five main-draw matches in the first grand slam of the year before last week, but will face Raonic with a place in the semi-finals on the line.

Pouille toppled Coric 6-7 (4-7) 6-4 7-5 7-6 (7-2), hitting 57 winners and serving 19 of the match's 43 aces to march on in his first major since appointing Amelie Mauresmo as coach.

The 24-year-old will be making his third quarter-final appearance at a grand slam, having reached the same stage at Wimbledon and the US Open in 2016.

The Frenchman levels @la_pouille ties things up on @melbournearena against Borna Coric, clinching the second set 6-4.#AusOpen pic.twitter.com/U0vc6v3EzA

— #AusOpen (@AustralianOpen) January 21, 2019