The Watch List highlights the must-know storylines for the upcoming week in tennis. This week the tours begin their transition to clay, with three of four tournaments taking place on red (and green) dirt.
Family Circle Cup
The Premier-level tournament in Charleston won't have Serena Williams to top its field this year, as she and Venus have opted to skip the tournament for the first time since 2011. The tournament got a late boost when top seed Eugenie Bouchard—in need of matches, wins, and confidence—took a late wildcard in the tournament, where she made the semifinals last year. She's joined by Ekaterina Makarova, defending champion Andrea Petkovic and Sara Errani as the top four seeds. Also in the draw are seventh-seed Madison Keys, Jelena Jankovic and a seemingly resurgent Sloane Stephens. Possible match to watch: Stephens could play Bouchard in the third round.
U.S. Men's Clay Court Championships
Can John Isner keep his good run of form going on clay in Houston? A champion in 2013, the top American is back in the Top 20 after a strong week in Miami, where he beat Grigor Dimitrov, Milos Raonic and Kei Nishikori to make the semifinals. He's the No. 4 seed behind top seed Feliciano Lopez, Roberto Bautista Agut and Kevin Anderson. Defending champion Fernando Verdasco and Jack Sock are also in the draw. Two notable wildcards are Lleyton Hewitt and Janko Tipsarevic, who is set to play his first singles match since 2013.
Agnieszka Radwanska returns home to top the field in Katowice, Poland. Stuck in a slump and still searching for her first title in the last eight months, the Pole needs a strong title run to jumpstart her season. Defending champion Alize Cornet is the No. 2 seed. Look for No. 3 seed Camila Giorgi, who made the final last year, to play the role of a possible spoiler.
Grand Prix Hassan II (Casablanca, Morrocco)
Fact of the day: The ATP's only stop in Africa, the Grand Prix Hassan II tournament is entirely funded by King Mohammed VI. Defending champion Guillermo Garcia-Lopez, Martin Klizan, Jiri Vesely and Marcel Granollers are the top four seeds.