LISTEN TO GRAEMA AGARS TALK WITH D'ARCY AND GORAN ABOVE
Ivo Karlovic miraculously took his match against Kei Nishikori into a decider after losing the first two sets but suffered a heartbreaking blow when he was toppled in a fifth set tiebreak.
The 39-year-old — the oldest man in the draw — produced a vintage serving display and won the fourth set with four consecutive aces to take his total up to 47 for the match.
The game before he iced the set, Karlovic broke No. 8 seed Nishikori to love for the second time as the tennis world reacted with shock to the incredible comeback.
Tennis coach and ESPN analyst Brad Gilbert was among those to express their admiration for Karlovic, tweeting: "Are you kidding?"
Nishikori then staged a remarkable recovery of his down. Serving at 4-4 in the fifth set, the Japanese star was down 0-40 but clawed his way back to win the game before Karlovic held serve to make it 5-5.
Both players held their next service games and the deciding set went to a tiebreak.
Drama struck when Karlovic was down 5-6 in the first-to-10 breaker. A Karlovic ball was called long and Nishikori hit the half volley into the net.
However, the Croatian challenged the call and Hawkeye showed the ball clipped the baseline and was actually in. Instead of replaying the point, it was awarded to Karlovic because the umpire deemed Nishikori would never have kept the ball in play even if he knew it was good.
Nishikori wagged his finger and had a crack at the umpire, but the umpire stood his ground.
That made it 6-6 and then 6-7 when Karlovic won the next point but incredibly, Nishikori won two points on Karlovic's serve and gave himself two match points when he went up 9-7. He thumped a return winner at his first opportunity to clinch a thrilling win.
Elsewhere, Ukranian Elina Svitolina took just 67 minutes to thunder past Viktoria Kuzmova and reach the third round.
But after the match, it was the man sitting in her players box that had tongues wagging of a potential romantic pairing.
French star Gael Monfils, who was knocked out yesterday in a five-setter by American Taylor Fritz, was lending his support to Svitolina.
Asked about Monfils sitting in her players box, Svitolina was put in an awkward spot. "Yeah...," she laughed followed by a long pause.
"Everyone saw him so he's supporting me, and hopefully we'll see him more in the future, not only in my box but on the court as well."
Monfils has previously dated fellow tennis pro Dominika Cibulkova and Australian Chelsea Altman, who is now married to AFL player Tyson Goldsack.
On the court, the sixth seed didn't have it all her own way in the first before demolishing Kuzmova in the second set.
Svitolina, a quarter finalist in last years' open, will play Karolina Pliskova after she recorded a 4-6 6-1 6-0 win over Madison Brengle.
Pliskova broke the American player's serve six times in seven chances after dropping the opening set. She also sent down seven aces and had 14 service winners.
The seventh-seeded Pliskova has now won all three times she has played Brengle. Pliskova has advanced to the quarterfinals each of the last two years at Melbourne Park, including a loss to eventual finalist Simona Halep last year.