Karlovic and Zeballos played the longest match, as measured by games played, in Australian Open history. Their fifth set went to 42 games before finally Karlovic prevailed. As incredible as the length of the match was the fact that Karlovic thundered down a record 75 aces. 75!

When Djokovic walked onto Rod Laver arena to play Verdasco, out on court 19 Karlovic and Zeballos were just kicking off their fifth set.

Djokovic then beat Verdasco, had toweled down, changed shirt, done an on-court interview, gone inside, spoken to his coach and sundry officials, perhaps even took in a meal and still the Croatian veteran and his dogged Argentinian opponent toiled.

Djokovic accounted for Verdasco – a former world top ten player who beat Rafael Nadal in the first round last year– in a pleasingly regulation two hours and twenty minutes against. Job done. Round two.

Karlovic, the 20th seed was working slightly harder. He went two sets down, then got back to level it before the marathon fifth set began.

That fifth set lasted 157 minutes – more than a quarter of an hour longer than Djokovic's entire match – before finally Zabellos wilted on serve. He resisted one match point but flayed a ball wide on his next to give the Croatian his hard-earned victory.

Their match began in 37 degree mid-afternoon heat and ended under dim lights exactly five and a quarter hours later with the 37-year-old Karlovic winning 6-7, 3-6, 7-5, 6-2, 22-20. Organisers had had to dispatch ball boys for more energy drinks to keep the pair going.

It was no Isner-Mahut but it was close. Remember that one? In 2010 at Wimbledon John Isner beat Frenchman Nicolas Mehut over 11 hours and five minutes - and three days' play – in a match that went to 183 games including a scarcely believable fifth set that stretched to 70-68.

Karlovic had thoughts of that match in mind during that fifth set. Perversely he was hoping it went longer than that match, not shorter.

"I was thinking about that other match Isner against Mahut. I was hoping little bit it could go this long so I could also have record. This is also good like this," he laughed.

"This is what I will, after my career, remember. If it was easy match or I lost easy, I wouldn't remember. But this one definitely I will remember forever."

While Tuesday night's match was the longest in terms of games at an Australian Open it was still shorter by 38 minutes of the longest match at Melbourne - the 2012 final between Novak Djokovic and Rafa Nadal that went five hours and 53 minutes.

The happiest man about the marathon match was Australia's Andrew Whittington who plays Karlovic next round.

Coincidentally Zabellos was the player who only a fortnight ago asked for a selfie with Djokovic in Qatar after the former world No.1 beat him in a brisk two sets.