by: Ben Stevens
If the story of Sunday was two current greats suffering monumental upsets, Monday was all about two all-time greats once again asserting themselves.
As if this tournament needed any more intrigue, it now has the very real possibility of crowning not just a new women’s record titleholder in Serena Williams, but eight years after his only AO championship, Rafael Nadal as well. The stars of day 8, Serena and Rafa are both firmly on track for the finals, and it’s going to take nothing short of a tidal wave to stop them.
The fourth round in the books, Tuesday marks the beginning of the quarterfinals with four highly enticing matchups. Whether looking for a potential upset, a 50-50 prospect or a highwire slugfest, read on for a preview of everything Day 9 has to offer.
(All matches listed in order of play)
Venus Williams (USA)  v Anastasia Pavlyuchenkova (RUS) 
Perhaps a bit shrouded by all the general craziness at the open, the 36-year-old Williams’ run through the draw has been fantastic to see. Playing a fellow massive hitter in Pavlyuchenkova, this match should have plenty of fireworks as both women won’t want to concede an inch on the baseline. The head-to-head rests at 3-2, but they haven’t played since one encounter in 2014 and before that, not since the turn of the decade. Pavyluchenkova showed in her match against Svetlana Kuznetsova that she was firing on all cylinders, and if she can keep that up and test Williams on her serve, we could be in for an epic encounter.
Coco Vandeweghe (USA) v Garbine Muguruza (ESP)  (Not before 1:30 pm local)
Yet to drop a set in the tournament, 7 seed Muguruza could be in for a rude awakening against the streaking Vandeweghe. She may be faking it till she makes it, but in her disembowelling of world no. 1 Angelique Kerber, Vandeweghe showed she is very much the real deal, and with a 2-1 head-to-head advantage, should be confident of repeating that success here. At a deficit in pure baseline power, Muguruza’s best chance of survival will come from aggressively attacking the open court and keeping Vandeweghe from stepping-in on rallies – a big ask of any woman playing her right now, but something of which the Spaniard is capable. If Muguruza can frustrate the American into breaking racquets instead of service games, she’s got a chance, otherwise expect the upsets to continue.
Stan Wawrinka (SUI)  v Jo-Wilfried Tsonga (FRA) 
If you like temperamental sluggers who crack winners like they’re going out of style, this is the match for you. On his day either is capable of hitting any player off the court, and when they play matches tend to resemble a game of Battleship – minus the explosions and Rihanna – as momentum can shift rapidly back-and-forth depending on who has the range of their groundstroke missiles. The two have played each other seven times – with Wawrinka leading 4-3 – but more importantly, in the three grand slam matches they’ve played (all at Roland Garros), they’ve played 14 of a possible 15 sets. There’s every reason to expect their titanic struggle to continue in Melbourne, and you’d be remiss not to watch.
Roger Federer (SUI)  v Mischa Zverev (GER) – Night session (7 pm local start)
The quarterfinal everyone wanted – well, half of it anyway, Federer finds himself up against surprise package Mischa Zverev in a matchup more suited for Wimbledon than the Australian Open. Playing classic serve-and-volley tennis with a forehand best described as “takeback optional”, Zverev was able to frustrate a clearly subpar Andy Murray by speeding up the tempo of points, hitting side-to-side from the baseline before charging the net at the slightest opportunity. Will that gameplan work as successfully against Federer? Probably not. It’s no secret that Federer likes to play fast, and Zverev’s caution-to-the-wind approaches will make him extremely vulnerable to the usual Federer passing brilliance. If Zverev is to win, he’ll need a miracle – but then again, he’s already done it once.