Watch List: Tours kick off in Houston, Katowice and Casablanca

After a tough loss to Serbia in the Davis Cup quarterfinals this weekend, John Isner and fellow American Sam Querrey will head to the ATP 250 event in Houston.

After a tough loss to Serbia in the Davis Cup quarterfinals this weekend, John Isner and fellow American Sam Querrey will head to the ATP 250 event in Houston. (Matthew Stockman/Getty Images)

The Watch List spotlights the must-know storylines for the upcoming week in tennis. This week, the top players take a much needed break after their month-long stint on hard courts and Davis Cup matches, but the tours officially kick off the clay court season in Houston, Katowice, and Casablanca.  

Men's Clay Court Championships

[Complete Draw]

The sole red clay tournament in North America will get underway on Monday at the ATP 250 event at the River Oaks Country Club in Houston. The event will welcome the top two Americans, Sam Querrey and John Isner, as well as top-seed Nicolas Almagro, Tommy Haas, and defending champion Juan Monaco. Expect some upsets early, as Querrey and Isner will be coming off a tough Davis Cup weekend in Boise, Idaho, while Monaco is still seeking his first ATP win of the season.

One name to watch is Gael Monfils. The Frenchman, now ranked No. 104, skipped the North American hard courts and hasn't played since February in Marseille, where he lost in the first round to Marcel Granollers. He's been a solid pick to make the quarterfinals or better at the French Open the last few years, so his clay build-up will be one to keep an eye on.

Potential early-round matches to watch: Gael Monfils vs. James Blake (first round), Fernando Verdasco vs. Steve Johnson (first round), John Isner vs. Ryan Harrison (first round), Isner/Harrison vs. Jack Sock (second round), Nicolas Almagro vs. Gael Monfils (second round), Tommy Haas vs. John Isner (third round).

BNP Paribas Katowice Open

[Complete Draw]

The inaugural WTA International tournament in Katowice, Poland (pronounced Katto-vittse, in case you're wondering), will oddly go forward without Poland's No. 1, Agnieszka Radwanska. Due to WTA rules that restrict the number of lower-level tournaments a Top 10 player may enter, Radwanska already burned her allotment for the first half of the year by playing Auckland in January, but will be in town to support the event and play an exhibition. The tournament also wasn't able to secure the other two top players with strong Polish ties, Angelique Kerber and Caroline Wozniacki, the latter of whom will be in Augusta supporting boyfriend Rory McIlroy. Instead, eighth-ranked Petra Kvitova tops the field, followed by Roberta Vinci, Klara Zakopalova, and Julia Goerges.

One return to note in the draw: Kaia Kanepi. The Estonian, who made the French Open quarterfinals last year, will play her first tournament since Tokyo last fall after suffering a foot injury. She's unpredictable and inconsistent as all heck, but if she gets on a run she can be dangerous on clay.

Grand Prix Hassan II

[Complete Draw]