10 story lines to watch during the ATP's clay season

With the conclusion of the Miami Open on Easter Sunday, the ATP World Tour now moves into its only full-time clay season, which is a nine-week period that culminates in the French Open, which is the only major that is played on the clay. Here is a look at the most important story lines going into the clay season:

1. Djokovic looking to complete career grand slam. Ever since Novak Djokovic won the title at the US Open in 2011, nothing has been more important to him than winning the Roland Garros title to complete the career grand slam. Also, nobody has won both the Australian Open and Roland Garros in the same season since Jim Courier in 1992. In all three attempts to win Roland Garros since winning the US Open, Djokovic has come up short, losing to Rafael Nadal on all three occasions. Djokovic will be 28 years-old at this year's Roland Garros, so time is running out for the Serb.

2. Nadal has to defend 3,870 points. To say that Nadal has been in a slump since winning Roland Garros last year would be a massive understatement. The Spaniard has only reached two semifinals of events since then and both were small clay-court events in South America. If Nadal doesn't defend any of his points, he will drop all the way down to No. 26 in the world. Of course, he will defend some of those points and the fall won't be that drastic.

However, if he does not have a great start to his clay season, he could easily be seeded as low as No. 9 at Roland Garros, since only 850 points separate him from current world No. 9 Stan Wawrinka, who also has a Monte Carlo title to defend. However, if Nadal is seeded anywhere lower than five he will have to go through a top four seed in the quarterfinals. And if he is as low as No. 9, he would have to beat a higher seeded player just to get to the quarterfinals, setting up all sorts of possibilities for wacky draws. Bottom line is though, that if Nadal does not get out of his slump immediately, his ranking is going to drop to places it hasn't been in almost a decade.

3. American clay court challenger swing. Following the tournament in Houston, the US clay season switches over to the Challenger Tour, where there are three consecutive events in Sarasota, Savannah, and Tallahassee. At those tournaments, the American that earns the most points at two of the events (whichever two of the three that he scores best in) will receive a wild card into the Roland Garros main draw. The last three to win the wildcard were Robby Ginepri (2014), Alex Kuznetsov (2013), and Brian Baker (2012), who defeated Xavier Malisse in the first round before taking No. 11 seed Gilles Simon to five sets in the second round.
Some of the Americans competing for the wild card will be:
122. Ryan Harrison
141. Austin Krajicek
166. Bjorn Fratangelo
168. Chase Buchanan
177. Jared Donaldson
189. Rajeev Ram
195. Dennis Novikov
210. Jarmere Jenkins
221. Alex Kuznetsov
463. Tennys Sandgren

Tim Smyczek will be the No. 1 seed in Savannah, but the No. 6 American will get a direct entrance into Roland Garros. Also, a number of the teenage Americans could be getting wildcards into these events, giving them a chance to compete for their first main draw appearance in a grand slam.

4. Murray looking for first career final on clay. Andy Murray has been ranked as high as No. 2 in the world in his career and won grand slam titles on hard and grass courts, but when it comes to clay, the Brit cannot get over the semifinal hump. Murray did win three clay court titles as a teenager on the futures level, but on the Challenger and ATP World Tours, he has never won a semifinal on clay. Murray is riding a six-match losing streak in clay court semifinals that has lasted over a decade already. Murray is scheduled to be the No. 1 seed in Munich. He is the only top 10 player in the draw, so we may finally see the streak come to an end in the German clay tournament.

5. Raonic looking to break top 5 for first time in his career. Milos Raonic has just 270 points to defend between now and Rome, and during that span, he will play in Monte Carlo, Barcelona, and Madrid. The Canadian is currently only 185 points behind current world No. 5 Rafael Nadal, who as mentioned before has a ton to defend. He is also only 210 points behind Kei Nishikori, who has a title to defend in Barcelona and finalist points in Madrid. Raonic could easily move all the way up to No. 4 in the world in just a month's time.

6. Goffin's 20-match clay winning streak and push to the top 10. Before the year started I said that nobody would crack the top 10 for the first time in their career this year, and so far that prediction is looking pretty good. However, if I am wrong, it will be because David Goffin goes on a big run on the clay this year. He did it last year winning 20 consecutive matches on the post-Wimbledon clay swing. He has just 45 points to defend between now and Roland Garros, but he would still need close to 1800 more points to crack the top 10. He is scheduled to play Munich along with the four other main clay events.

7. Istanbul and Geneva debut on the ATP. With the termination of the tournaments in Belgrade, and Dusseldorf, two slots opened up in the clay season, and they were filled by Istanbul and Geneva. Istanbul has been a successful stop on the WTA tour, but is just now making its debut on the ATP, and Roger Federer will be there to help grow the event. He will be the No. 1 seed. No. 2 seed Grigor Dimitrov will also be a fan favorite as a Bulgarian playing in front of the Turkish crowd. Meanwhile, Geneva's entry list will be highlighted by Swiss Stan Wawrinka.

8. Del Potro, Sock, and Almagro continue comebacks. Juan Martin del Potro and Nicolas Almagro have been making slow comebacks, but being back on the clay will be good for both of them. Almagro has always played his best on the clay, and for the Argentine, the clay should make the injury to his left wrist less of an issue. Being on clay should give him more time to run around his backhand, so that he won't have to hit as many two-handed backhands.

For Jack Sock, clay has always been his worst surface, but he seems to improve every year on the clay. He has had the most successful comeback so far, and while he was gone he had very little to defend, meaning his ranking did not take a big fall down the rankings.

9. Berdych trying to extend hot start to 2015 over to clay. This has quietly been a very good year for the Czech, who is currently ranked No. 3 in the Race to London rankings. He has reached the semifinals of all, but one tournament in 2015, which was Indian Wells, where he reached the quarterfinals. However, he isn't getting a lot of attention, because he hasn't won a title yet, which is pretty normal for Berdych. The current world No.8 had a decent year on clay last year reaching the final of Oieras and quarterfinals of Roland Garros and Madrid. With the way his season has started, he is going to expect to do even better this time around.

10. Which American will find success on the red dirt? There are currently six players from the United States in the top 70 in the world, but none of them would call clay even their second best surface. At least, not honestly. The six players have a combined record of 84-108 on clay. John Isner and Jack Sock are the only ones with winning records and it is just barely over .500 and with a much smaller sample size than their hard court records. Isner and Sock are the ones in the best form going into the clay season as well. None of the six have anything significant to defend, so this could be a great clay season for Americans or another missed opportunity.

Current Rankings: Points to defend on clay in parenthesis
1. Novak Djokovic 13205 (2560)
2. Roger Federer 8895       (790)
3. Andy Murray 6060        (990)
4. Kei Nishikori 5280        (1110)
5. Rafael Nadal 5255         (3870)
6. Milos Raonic 5070         (990)
7. David Ferrer 4670          (900)
8. Tomas Berdych 4510     (780)
9. Stan Wawrinka 4405      (1110)
10. Marin Cilic 3360           (360)