How good has Maria Sharapova been on clay lately? Can Simona Halep go higher in the rankings? Why is Dinara Safina in town? Get ready for a big, big week right here.
WTA Staff

Every week on we'll bring you 10 of the most important things to know for the week - who's playing, upcoming milestones... this week the Road To Singapore goes through Madrid.

1) Serena Williams leads an absolutely packed field in Madrid.
Nine Top 10 players, led by Williams, are at the Mutua Madrid Open this week. The World No.1 is going for her third straight title at the Premier Mandatory-level event, and she won her opening match on Sunday against Belinda Bencic (read about that match here). Williams is trying to win a WTA event three years in a row for the second time - she three-peated in Miami in 2002, 2003 and 2004.

2) Li Na is playing for the first time in more than five weeks.
The last time Li played a match, it was the finals of Miami on Saturday, March 29 - more than five weeks ago. She was unable to play in Stuttgart due to a right knee injury. But the good news for Li is that she has very little to defend the rest of the clay court season, falling early at all three of these events last year - first round in Madrid, third round in Rome and second round at Roland Garros.

3) Simona Halep has a shot at No.4 here.
Halep, who is already the highest-ranked Romanian player in WTA history at No.5 in the world, would improve her career-high to No.4 if she wins the title this week. Follow along on the WTA rising star's quest as she brings us this week's WTA Blog - and don't forget to send your questions in for her!

4) Maria Sharapova hasn't lost to anyone on clay except Serena in almost three years.
Since falling to Li in the semifinals of the 2011 French Open, Sharapova is an impressive 41-3 on clay courts, her only three losses coming to Williams, and all in straight sets too - in the 2012 Madrid quarterfinals (6-1, 6-3), the 2013 Madrid final (6-1, 6-4) and the 2013 French Open final (6-4, 6-4).

5) Carla Suárez Navarro is on a roll, and she's on home soil this week.
Suárez Navarro had a fantastic week in Oeiras last week, not only winning the first WTA title of her career (in her sixth attempt in a WTA final) but also becoming the WTA's new match win leader, her win over Svetlana Kuznetsova in the final being her 26th of the year (two more than any other player).

The Spanish No.1 will open her Madrid campaign on Monday night against Yvonne Meusburger.

6) The doubles field in Madrid is packed too.
The Top 10 teams on the Road To Singapore doubles leaderboard are all in Madrid, led by the world's No.1 doubles team, Hsieh Su-Wei and Peng Shuai, and one of the most popular teams out there, Martina Hingis and Sabine Lisicki. Former No.1s Liezel Huber and Lisa Raymond are also in the mix.

7) Dinara Safina is officially retiring from professional tennis later this week.
Safina, a three-time Grand Slam finalist and World No.1, has not played since this very tournament in 2011 - and after three years of inactivity due to a back injury, she will be announcing her retirement from the sport on Finals Day next weekend. Click here to tell us your favorite Safina moment.

8) WTA Trivia: The greatest stretch of Safina's career was arguably her European clay court season in 2009, as she went 16-2 with back-to-back title runs in Rome and Madrid sandwiched between two finals in Stuttgart and Roland Garros. The same player beat her in both of those finals - who was it?

9) WTA Trivia: Suárez Navarro is one of three Spaniards ever to reach the Top 15, alongside Arantxa Sánchez-Vicario and Conchita Martínez, who went as high as No.1 and No.2, respectively. Three other Spaniards made the Top 20 though, peaking in the No.16 to No.20 range - can you name them?

10) Go to WTA TV developed by Xerox to find out where you can watch Madrid on TV!

Maria Jose Martinez Sanchez

* WTA Trivia answers: The player who beat Safina twice during that stretch was Kuznetsova, and the other three Spaniards to reach the Top 20 were Magüi Serna (who reached No.19 in 2004), Anabel Medina Garrigues (No.16 in 2009) and María José Martínez Sánchez (No.19 in 2010).