1. Who is healthy?

Top seed Angieszka Radwanska reclaimed the World No.2 ranking last week when reigning Australian Open champion Angelique Kerber failed to defend her title at the Volvo Car Open. Arguably the most consistent player of the last six months, Radwanska has reached the semifinals or better of all but one of her five WTA appearances in 2016 – that being a hard-fought Miami Open loss to eventual semifinalist Timea Bacsinszky in the round of 16.

However, all of those matches might be catching up with the Pole, who withdrew from her home tournament in Katowice and the Fed Cup World Group II Play-off due to a right shoulder injury. Heading onto what has traditionally been her least successful surface, Radwanska has few points to defend through the French Open, winning just two matches during last season’s clay court swing.

Click here to check out the Stuttgart draw.

Still, Stuttgart’s notoriously stacked draw means she will have to hit the ground running after a first round bye, facing one of two Fed Cup heroines in Andrea Petkovic and Kristina Mladenovic. No.8 seed Lucie Safarova, Karolina Pliskova, and 2008 French Open champion Ana Ivanovic are all possible quarterfinal opponents.

With far more to defend ahead of the second Grand Slam of 2016 is former French Open finalist Simona Halep. One of the most natural clay court players in the field, the Romanian reached the semifinals of Stuttgart and Rome, but admitted to picking up a left ankle injury in her three-set win over Andrea Petkovic in Fed Cup. Unsure if she would play her second match against Germany on Sunday, Halep won only four games against Kerber, who had never beaten Halep in three previous encounters.

Seeded fourth in Stuttgart, the former World No.2 will have a few extra days ot recover, but is in a section full of dangerous floaters like Anastasia Pavlyuchenkova, 2011 champion Julia Goerges, Alizé Cornet and Ekaterina Makarova. No.6 seed Roberta Vinci rounds out the top half of the draw.

2. Can Kerber and Suárez Navarro rebound on red clay?

Kerber won the second of four Premier titles in Stuttgart last year, outlasting an in-form Caroline Wozniacki in three grueling sets. The German shook off a minor post-Melbourne slump to reach the semifinals in Miami and Charleston, where a viral illness forced her to retire against Sloane Stephens. More at home on faster surfaces, Kerber can still get things down in Stuttgart’s slow conditions; seeded second, she’ll play either a qualifier or countrywoman Annika Beck, whom she beat en route to her Australian Open title.

Her possible quarterfinal opponent could be another Aussie redux in semifinalist Johanna Konta, but all eyes will be on No.7 seed Carla Suárez Navarro. The story of the season’s first six weeks, Suárez Navarro rocketed up the rankings with a solid Middle Eastern Swing and a title in Doha, but an ankle injury halted her momentum and her inability to defend her Miami Open points caused her to fall from No.6 to No.11.

A finalist last year in Rome, the Spaniard had few problems in Fed Cup, dropping just two games against Roberta Vinci. She may trail Kerber in the overall head-to-head, but their only clay court meeting came two years ago in Stuttgart. The winner? Suárez Navarro, in straight sets.

3. Will Garbiñe Muguruza bring her Fed Cup form to Stuttgart?

Despite a slow start to 2016, Muguruza appeared to be putting the pieces together in Miami, playing one of the best matches of the year against former No.1 Victoria Azarenka. Traveling to Lleida for a relegation Fed Cup tie against the once unstoppable Italians, the Spaniard made a seamless transition to the terre battue with a pair of straight set victories over 2010 French Open champion Francesca Schiavone and Vinci, whom she defeated, 6-2, 6-2.

Known for her breakout run to the 2015 Wimbledon final, Muguruza is perfectly capable on clay, having twice made the quarterfinals of Roland Garros – defeating World No.1 Serena Williams in the second round back in 2014. The No.3 seed in Stuttgart, she will open against Sabine Lisicki or Timea Babos, a fast-rising Hungarian who nearly upset Kerber under the lights in Miami.

No.5 seed Petra Kvitova is her projected quarterfinal opponent, but Monica Niculescu or Caroline Garcia could just as easily take their own impressive form from Fed Cup to take out the two-time Wimbledon winner.

4. Which hometown favorite is poised for a breakout run?

Though Germany boasts six women in the Top 60, only four may be eligible for the Olympic Summer Games; with less than two months before the teams are selected, the results through the clay court swing will be crucial to determining which women make the cut to qualify for Rio.

How tight is the race for the German Olympic team? As of April 18th, No.4 and No.5 Sabine Lisicki and Anna-Lena Friedsam are separated by just two places in the WTA rankings, at No.50 and No.52, respectively. Not too far behind at No.59, Julia Goerges is in the midst of a stellar season, having already reached a final in Auckland and another in doubles at the BNP Paribas Open.

All six women are in action this week in Stuttgart, led by Kerber and Petkovic, who are the only two ranked inside the Top 30. Goerges defeated then-No.1 Wozniacki to win the title here in 2011, while Lisicki will be hard-pressed to turn around a disappointing start to her season. Will any make strides towards those coveted Olympic spots?

5. How will Santina fare as they search for a second wind?

Martina Hingis and Sania Mirza began this season much as they ended the last, roaring through back-to-back titles in Brisbane, Sydney, Melbourne, and St. Petersburg before their 41-match winning streak came to an end in Doha. Since narrowly losing to Daria Kasatkina and Elena Vesnina in a match tie-break, Santina have been unable to string together wins, losing in the round of 16 in both Indian Wells and Miami – titles they won to cement their partnership in 2015.

Opting against the trip to Charleston, Hingis and Mirza look to regain their mojo as they aim to achieve their ultimate goal of a fourth straight major tournament, a “Santina Slam.”

Playing on their least favorite surface, the co-No.1s should be able to play their way into form in the 16-team draw with only four seeds. Their biggest opposition looks to be No.2 seeds Caroline Garcia and Kristina Mladenovic. The French Connection swept the Charleston title in Santina’s absence – defeating reigning French Open champions Bethanie Mattek-Sands and Lucie Safarova in the final – and battled through a decisive doubles rubber to send France into the Fed Cup final on Sunday.

Under the radar is the unseeded Kveta Peschke. The former No.1 and 2011 Wimbledon champion is playing her first tournament since last year in Dubai; pairing with Anna-Lena Groenefeld, Peschke will open against No.4 seeds Raquel Atawo and Alicja Rosolska.

All photos courtesy of Getty Images.