Tennis: Pablo Carreno Busta exploded at the end of his five-set loss to Kei Nishikori

Spanish hothead Pablo Carreno Busta has apologised for the moment he stormed off court before turning around and roaring at the chair umpire in a stunning post-match meltdown.

The No. 23 seed’s furious blow up has completely overshadowed the epic, five-hour marathon which saw Japanese superstar Kei Nishikori progress through to the quarterfinals, despite finding himself two sets down.

Nishikori was pushed to breaking point playing his third five-set thriller at this year’s Open.

Carreno Busta went from ice calm to breaking point in an instant when a controversial umpire decision awarded a point to Nishikori in a tense fifth set tie-break.

The 305-minute marathon had it all even before the moment Carreno Busta suffered a complete meltdown with the match on the line at the death.

Nishikori prevailed after finding himself down 8-5. He held his nerve as his opponent exploded in the dying minutes.

THE CALL THAT MADE HIM LOSE IT

The match was turned on its head by a controversial chair umpire decision following a late linesman’s call which ruled Carreno Busta would not have returned a Nishikori backhand.

Carreno Busta furiously argued he had stopped playing because of the overruled line call, but the point was still awarded to Nishikori.

Chair umpire Thomas Sweeney awarded Nishikori a point after Carreno Busta’s shot had been wrongly called out, but Nishikori played on and hit a winner anyway.

Carreno Busta’s claim that he could have returned Nishikori’s shot was waved away controversially by the official, who refused to replay the point.

Carreno Busta then fumed in a lengthy tirade toward the match official. When play resumed he appeared to have lost focus and coughed up the last five points of the match to gift marathon man Nishikori a spot in the quarter-finals.

Having already been on court for almost nine hours before his third round match, Nishikori found himself down two sets before he recovered to take the match 6-7 4-6 7-6 6-4 7-6 (10-8) — the longest match at this year’s slam.

The drama was only just beginning for Carreno Busta after Nishikori sank to his knees following match point.

THE MATCH AFTER THE MATCH

The No. 23 seed snubbed the chair umpire for a hand shake and was then booed off the court on Margaret Court Arena. He bolted to the other side of the court to shake Nishikori’s hand, grabbed his gear and headed for the exit.

The heckling clearly didn’t sit well with Carreno Busta and he made it known, turning around in the middle of his stride to roar back at the crowd and the chair umpire.

It was a sad end to a modern classic, which had earlier been making headlines for all the right reasons.

His screams toward the umpire were described as “livid” by some tennis commentators.

Aussie tennis legend John Fitzgerald also lamented Carreno Busta’s brain snap.

“He is not showing his true character,” Fitzgerald told Channel 9. “He can hold his head high. He just lost it a little bit at the end. You have to admire both players. Two warriors.

“I’m speechless. It didn’t deserve that little bit of twist at the end. Let’s not let that take away from the spectacle we just saw.”

Carreno Busta also said he hoped the match is not remembered for his dramatic meltdown, but for the five hour contest that ebbed and flowed before it.

“The way I left the court was not right, and I’m so sorry, because that’s not me,” he said in his post-match press conference.

“I am very sad because after five hours of fighting the way that I leave from the court wasn’t correct.

“I think that the referee missed. And when I tried to leave as fast as possible, I lost the head. It’s tough for me to leave the Australian Open like this because I thought I played really well. It’s tough to leave like this.”

He said the controversial point at 8-5 in the final tie-break simply had to be replayed because of the linesman’s call.

Earlier, as the match ticked over four hours, Nishikori was broken as he served for the match with a break up his sleeve.

It was a crushing blow for the Japanese star after he mounted an emotional fightback from two sets down to send their contest into a fifth set.

While serving for the match Nishikori completely froze and clanked three unforced errors in the one service game to allow Carreno Busta to level at 5-5.

The match then headed to a fifth set tie-break and has Nishikori heading to the last eight having spent more than 13 hours and 40 on court at Melbourne Park.