ICYMI: Djokovic crumbles, Raonic battles mystery illness, Serena sails

— -- MELBOURNE, Australia -- What. A. Match!

Twelve-time Grand Slam champion Novak Djokovic was sent packing from the tournament he's owned in recent years, after failing to hold off an inspired, and at times, remarkable Denis Istomin.

Djokovic entered the clash having won 39 of his past 40 Australian Open matches, but the world No. 117 wasn't to be perturbed and turned in his greatest ever performance to send the Serb crashing out after a brutal 4-hour, 48-minute 7-6 (8), 5-7, 2-6, 7-6 (5), 6-4 marathon.? READ MORE

Was this match? Djokovic's most shocking loss in his illustrious career? HARD TO ARGUE AGAINST IT

The numbers crunch:

• The last player to come from two sets to one down to defeat Djokovic was Jurgen Melzer in the quarterfinal of the 2010 French Open.
• In 33 matches prior, Djokovic had never lost to an opponent ranked outside the top 100 in majors.
• Istomin became just the fourth wild card in the Open era to defeat a top-two seed at a major, joining Pat Cash, James Blake and Nick Kyrgios. Istomin also snapped a 0-19 career record against top-four-ranked players.

Radwanska joins the Djoker

Within an hour of Djokovic's shock departure, women's No. 3 seed Agnieszka?Radwanska also bowed out to complete an afternoon of major upsets in Melbourne. The 27-year-old was wiped off the court by Mirjana Lucic-Baroni, who until this year hadn't won an Australian Open match since 1998, in a tidy 63 minutes, 6-3, 6-2.?

2017 marks the third time in Australian Open history, and the first since 1978, that two of the top four seeds failed to reach the third round after No. 4 seed Simona Halep?departed earlier this week in the first round.?

Unwell Raonic advances

Things appeared rosy for Canadian Milos Raonic in his straightforward 6-3, 6-4, 7-6 (4) win against? Gilles Muller, but the No. 3 seed had climbed out of bed feeling unwell just hours earlier.

Smashing 21 aces and 56 winners past his 33-year-old opponent, Raonic didn't appear to be suffering, but later admitted his illness had forced him to play well within himself.

Next up for Raonic is Frenchman Gilles Simon in the third round after he breezed by Rogerio Dutra Silva in just 96 minutes. Simon should not be underestimated at Melbourne Park, having last year come mightily close to knocking off eventual champion Djokovic in an epic fourth-round clash.

Williams sisters continue dream start

Serena?and Venus Williams?have played a combined eight sets of tennis at this year's Australian Open -- and eight sets they've won. The No. 2-seeded Serena overcame a stern challenge from Czech Lucie Safarova, but prevailed 6-3, 6-4.? READ MORE

Afterward, she got a little testy when a reporter questioned her form. Here's the brief exchange:

Q:?Looked a little bit of a scrappy performance. A few more unforced errors, a few double-faults.

Serena: I think that's a very negative thing to say. Are you serious?

Q: Just my observation.

Serena: Well, you should have been out there. That wasn't very kind. You should apologize. Do you want to apologize?

Q: I do. I'm sorry.

Serena: Thank you very much. That was a great performance. I played well. She's a former top-10 player. The last time we played together was in the finals of a Grand Slam.

You know, it's not an easy match. She's a really good player. You have to go for more, which obviously makes a few more errors.

The numbers crunch:

• Serena improved to a career record of 63-2 in the second round of Grand Slams -- the only losses coming against formidable players: Venus at the 1998 Australian Open and to Garbine Muguruza at the 2014 French Open.
• The 2017 Australian Open is the 46th time the Williams sisters have both reached the third round of a Grand Slam.
• Serena improved to a 10-0 career against Safarova, tied for the most wins she has against one opponent without a loss (Radwanska is the other).

Time for a coach?

He may have been sensationally dumped out of his home Slam, but rumors continue to swirl around who is set to take on the most challenging job in tennis: coaching Nick Kyrgios.

Pat Cash has emphatically ruled himself out. Brad Gilbert was, and then wasn't interested. Lleyton Hewitt is being urged to take it on.

One thing is certain; whoever takes on this job is going to have their hands full.