We're bringing you a daily notebook from the Australian Open this fortnight - food for thought on the first Grand Slam event of the year. Today, Courtney Nguyen takes us through the last 16.
WTA Staff

MELBOURNE, Australia - New names, young names, familiar names, resurgent names. The round of 16 is now set at the Australian Open. Here's how they got there:

The Favorites
The Top 2 seeds in Serena Williams and Maria Sharapova haven't had the smoothest of roads into the fourth round. Serena spent her first three matches vacillating between dominance and vulnerability, throwing in three bagel sets over three different opponents, while also having to save set points against former World No.2 Vera Zvonareva in the second round and rallying from a set down to Elina Svitolina on Saturday to advance.

Sharapova twice came within a point of exiting the tournament in the second round, saving two match points and rallying from two breaks down in the final set to beat Alexandra Panova, 6-1, 4-6, 7-5. "No matter how you prepare, what you did, once you get out there, everything starts from scratch," Sharapova said. "It was a tough day, but I pulled through." She rebounded by losing just two games to Zarina Diyas in the next round.

Simona Halep, Agnieszka Radwanska, and Eugenie Bouchard haven't lost a set through the first week, but it's been Radwanska and Bouchard who have been dominant. Radwanska has lost just nine games through three matches, while Bouchard has followed suit, losing just 14 games.

The Suriviving Seeds (Muguruza, Domi, Venus, Maka, Peng)
Venus Williams has been the story of the first week. The 34-year-old hasn't lost a match in 2015 - she walked away with the ASB Classic title to start her season - and she's into the fourth round of the Australian Open for the first time since 2010. On the brink of defeat in the third round to Camila Giorgi, Venus rallied from a set and 4-2 down to win 4-6, 7-6(3), 6-1.

Dominika Cibulkova appears to have put her 2014 struggles behind her and rediscovered that Melbourne magic that put her into the final here last year. She's lost just one set en route to the fourth round. Garbiñe Muguruza has had to battle through the first three rounds, going three sets in her last two matches to match her fourth round appearance last year.

The two remaining seeds who have made it easy for themselves are Ekaterina Makarova and Peng Shuai. Neither have dropped a set and Makarova came through a tough section that included a 6-4, 6-4 win over surging Czech star Karolina Pliskova.

The Floater
Vika, Vika, Vika. The most dangerous unseeded player in the draw has made good on that label. The two-time Australian Open champion has not lost a set through three rounds, which included wins over Sloane Stephens, Caroline Wozniacki, and Barbora Zahlavova Strycova. She is back to her fit and fighting form but doesn't want to compare the "New Vika" to the "Old Vika."

"I would never want to compare that because I think the game itself progressed a lot and I do feel I'm playing better than I was playing two years ago. I think the women's tennis level went up, so I don't like to compare the past. I just want to look forward to the future. I think my game evolved. I'm just heading towards 'better' rather than looking at how I used to play."

The Party Crashers (Madisons, Julia, Yanina, Begu)
Raise your hand if you had a Madison into the second week of the tournament. Good for you! Now raise your hand if you had two Madisons into the second week of the tournament. How about picking some lottery numbers for me?

The Australian Open will feature the first ever all-Madison round of 16 match on Monday when Madison Keys faces off against Madison Brengle. Keys booked her spot with a fantastic performance to defeat reigning Wimbledon champion Petra Kvitova 6-4, 7-5 in the third round, while Brengle has been riding high since stunning Andrea Petkovic in three sets in the first round.

Rounding out the field are Germany's Julia Goerges and Romania's Irina Camelia Begu. Goerges, ranked No.73, has found some of her best form this week, beating Belinda Bencic and then taking advantage of the opportunity afforded in the draw after Ana Ivanovic's shocking loss in the first round. Begu forged her own path by stunning Angelique Kerber in the first round and following it up with wins over Katerina Siniakova and Carina Witthoeft.

Full slate of Round of 16 matches:
Serena Williams vs Garbiñe Muguruza
Dominika Cibulkova vs Victoria Azarenka
Madison Keys vs Madison Brengle
Venus Williams vs Agnieszka Radwanska
Julia Goerges vs Ekaterina Makarova
Yanina Wickmayer vs Simona Halep
Eugenie Bouchard vs Irina-Camelia Begu
Peng Shuai vs Maria Sharapova