Anything can happen on the hard courts of Melbourne Park at the Australian Open. That was proven when top women's seed and five-time champion Serena Williams lost in Round 4 to Ana Ivanovic, thwarting her bid for an 18th major title.
That has been the most shocking development thus far in the first Grand Slam event of the 2014 season—even though Ivanovic is a former world No. 1.
While nothing much more stunning than that upset is likely to be on the horizon, there are still several marquee players in danger of being bounced early on Day 8.
Let's take a look at some of the stars that must be on their games Monday, Jan. 20 to ensure that they advance to the next stage of the tournament.
Victoria Azarenka (2) vs. Sloane Stephens (13)
The player who eliminated Williams last year is Sloane Stephens, and the 20-year-old American is seeking to build on the good vibes at this venue by knocking off another superstar in Victoria Azarenka.
Stephens has the talent and all-court game to take down her favored opponent, but she's struggled to find the consistency necessary to even win one singles titles to date. This would be a heck of a maiden triumph, and the fact that she's an underdog is something Stephens has embraced before.
However, there will be an undoubted heightened sense of urgency and focus coming from Azarenka, because she is now the prohibitive favorite to win the Australian Open since Williams has been bounced.
Azarenka is not taking her opponent lightly, per WTA.com:
Sloane is a great player and a very tough competitor. She has a great record here. It's going to be tough and every round is more challenging now. I'm looking forward to that match...I also feel like she's improved so much. She proved that she can handle big stages. She can play against top players. So it's always tough when a player like that knows how to handle themselves.
The two-time reigning champion beat Stephens in the semifinals last year 6-1, 6-4, yet it is worth noting that she failed to capitalize on five match points, allowing Stephens to hang tough in the second set.
With the amount of pressure Azarenka will be facing in a Melbourne three-peat bid, Stephens has a chance to be aggressive and play loose.
Then again, Azarenka has made sure to seize the title the previous two years without Williams to overcome, as the New York Times' Ben Rothenberg points out:
Kind of remarkable that Azarenka could 3-peat here without having to face Serena once. Not an easy obstacle to avoid in this era. #AusOpen— Ben Rothenberg (@BenRothenberg) January 19, 2014
This should be a three-set thriller, but look for Azarenka to pull it off due to her less erratic game and experience in dealing with the big stage.
Prediction: Azarenka wins; 6-3, 5-7, 6-4
Vengeance should be a theme in this match, and it's something Jo-Wilfried Tsonga isn't shying away from in battling perhaps the greatest champion in men's tennis history.
ATPWorldTour.com recorded what Tsonga had to say about clashing with Roger Federer, a 17-time Grand Slam champion:
For me it's the possibility to take revenge because last year I lost against him here in the quarter-finals. It's a good opportunity for me to play him again. And it's always nice to play against such a good player. The tournament continues for me and I'm feeling good.
The 32-year-old Federer seemed to be losing steam last season as his playing days are winding down, but an encouraging start to 2014 might suggest he has something left in the tank.
Federer has not dropped a single set en route to the Round of 16 after making it to the final in his only previous appearance of the current campaign.
As powerful and formidable as Tsonga is—he beat Federer in straight sets at last year's French Open—he will cause Federer enough problems to force a fourth set, but nothing further.
"Roger's Renaissance" could very well be a headline at Melbourne Park by the time this tournament is finished. But first, he must take care of his opponents one at a time and methodically. He will wear out Tsonga and advance to the quarterfinals without too much stress.
Prediction: Federer wins; 7-5, 7-6, 3-6, 6-2
Jelena Jankovic (8) vs. Simona Halep (11)
Which upset is most likely?
The big red flag for Jelena Jankovic entering this one is her poor form from the third round, where she hit just 12 winners compared to 33 unforced errors.
That doesn't guarantee she will play poorly against Simona Halep, but similar form will get her bounced from the year's first Grand Slam in swift fashion.
Halep had a bit of a wake-up call in the second round after losing the opening set to Varvara Lepchenko and roared back in dropping just one game for the remainder of the match.
The promising 22-year-old was the WTA's Most Improved Player after winning six singles titles in 2013. She is on the cusp of truly breaking out, reaching the fourth round in her second straight Grand Slam—the best efforts of Halep's young career.
Experience works in Jankovic's favor, but her status as the favorite and past top-ranked player puts more pressure on her to fend off her quickly ascending star opponent.
Jankovic has made a living attacking her foes from unexpected angles and responding to quality shots that could be winners. On the hard court, it is harder for her to respond, especially against such an athletic adversary in Halep.
Look for this one to go the distance but for Halep to break new ground and reach her first Grand Slam quarterfinal.
Prediction: Halep wins; 6-4, 6-7, 6-3