Roger Federer and Serena Williams are familiar champions but this year's Australian Open was one of the most unpredictable grand slams in recent memory.

Here, we take a look at five things we learned from a topsy-turvy tournament Down Under:

All's well again with Serena - but not Djokovic

After a disappointing 2016, Williams looked physically and mentally refreshed in Melbourne and if those two boxes stay ticked, she can win 30 grand slam titles never mind pass Margaret Court's all-time best of 24. Djokovic also arrived with a point to prove but left with only more questions to answer, the Serb enduring a shock second-round defeat to Uzbek wildcard Denis Istomin. After winning four grand slams in a row, he is now without a victory in three, as doubts about his commitment continue to fester. For Djokovic, a new season brought the same old problems.

Serena Williams looked back to her bast in Melbourne (Getty)

Forty the new 30 in the era of the oldies

Federer's vintage five-set victory over Rafael Nadal provided a fitting end to a retro-flavoured Australian Open, in which the Williams sisters reconvened in the women's final and 35-year-old Mirjana Lucic-Baroni reached the last four at a major tournament for the first time since 1999. This is the only grand slam in the Open era to have boasted four singles finalists aged 30 or older and it points to a very real shift in tennis' chronology. Players now stay fitter for longer, manage their schedules better and travel the world more comfortably, making the prospect of playing on far less daunting than it used to be. The game's old guard may stick around for a good while yet.

Dimitrov has matured, Kyrgios not so much

Andy Murray and Djokovic's early exits did not pave the way for a fresh-faced champion, or even runner-up, but Grigor Dimitrov does finally appear to have got his house in order. The Bulgarian has failed in recent years to live up to his 'Baby-Fed' billing but his run to the last four, which ended in a thrilling five-setter with Nadal, showed he is ready to win one of these. Others, however, missed the opportunity, in particular Nick Kyrgios, the combustible Australian who combusted again in a second-round defeat to Andreas Seppi. Kyrgios admitted after the match he needed a coach but until words are backed up by actions, or at least a change of attitude, the jury remains very much out.

Grigor Dimitrov gave a good account of himself Down Under (Getty)

Konta right in the mix for a grand slam title

For over a decade, Murray has been Britain's lone singles representative at the business end of major tournaments but with Konta, now there are two. The world number 10 came through a fiendish section of the draw without breaking sweat, before running into an inspired Serena Williams in the quarter-finals. It was a mark of her form that many felt Konta might beat the American and had she landed in the opposite half, she may well have been playing her in the final. It will almost certainly take a strong run at Wimbledon for her to become a household name at home but make no mistake, Konta is now a genuine grand slam contender.

Johanna Konta has a bright future ahead of her (Getty)

Never skip a photo with Dan Evans

Evans' mid-career surge continues unabated after the 26-year-old from Solihull dispatched Marin Cilic and Bernard Tomic during a superb run to the fourth round. Evans revelled in his success, aiming a barb on social media at Kevin Pietersen, who had made the mistake of snubbing his request for a photograph when they met in Melbourne's Crown Casino. Pietersen quickly apologised and Evans ended up with free tickets to the cricket star's next match at the MCG. After a rare early exit for Murray, Evans' strong form on and off court came as a welcome antidote for British tennis fans. He and Kyle Edmund will now fly the flag in the singles at next week's Davis Cup tie against Canada.