Clay can be the most demanding surface, and recently it has been the most predictable. Rafael Nadal has treated Roland Garros as his stomping ground, raising the Coupe de Mousquetaires in eight of the past nine years.
The world No. 1's surprising loss to David Ferrer in the Monte Carlo quarterfinals, combined with the right wrist injury that limited No. 2 Novak Djokovic in the second set of his Monte Carlo loss to Roger Federer, may give challengers a bit more hope before the start of clay-court Masters tournaments in Madrid and Rome.
Consider that since 1999, there has been one unseeded French Open champion (Gaston Gaudio in 2004), three unseeded runner-ups (Andrei Medvedev in 1999, Mariano Puerta in 2005 and Martin Verkerk in 2003), a 20th-seeded champion (Albert Costa in 2002) and a No. 23 seeded runner-up (Robin Soderling in 2009).
That's not to suggest a long shot will reach the French Open final in June, but it is a reminder that clay can be a shifting surface. With that in mind, here are our top 5 dark horse players to watch during this clay-court season. We define dark horse as a player ranked outside the top 10.
No. 13 Fabio Fognini
Strengths: Savvy court sense, sharp groundstrokes, a flair for angles and a mischievous mind are all assets Fognini has applied, posting a 16-3 record on dirt this season. Soft hands and the ability to close at the net enable Fognini to carve up opponents with a sculptor's creativity. He reached seven clay-court quarterfinals in 2013 and posted a career-best 13-match winning streak on dirt, sweeping successive titles at Stuttgart and Hamburg. His ability to take the ball early and redirect pace accurately are resources on return. Fognini finished fifth in return games won (31 percent) last season.
Shortcomings: Emotional volatility. The theatrical Italian's response to stress sometimes sends him into meltdown mode, shattering his concentration to collateral damage. Mood swings can cause Fognini to careen from smooth shot-making to casual indifference and when his inner clown comes out, matches can become a circus. He was booed by the Monte Carlo crowd for an apathetic attitude in each of the past two years. The 5-foot-10 Italian Davis Cup hero has a solid first serve, but his second serve can be shaky under pressure, contributing to his 4-29 career record versus top 10 opponents.
No. 16 Grigor Dimitrov
Strengths: Athleticism and an all-court game that can challenge the elite. Dimitrov beat Djokovic on clay in Madrid last year, defeated No. 3 David Ferrer to win his first title in Stockholm in October, and topped Andy Murray en route to the Acapulco title in March. His first serve, forehand, movement and ability to improvise on the run are all weapons.
Shortcomings: Shot selection, inconsistency and underwhelming results in Masters and majors. Dimitrov can dazzle winning style points, but can lack clarity on crucial points. When pushed back behind the baseline, his one-handed backhand can be vulnerable. He has won just three career matches at Roland Garros, and his best performance in a clay-court Masters was a quarterfinal result at Monte Carlo last year. Both of Dimitrov's titles have come on hard courts, and though he owns a .568 winning percentage on dirt, the 22-year-old Bulgarian sometimes suffers an identity crisis on clay and looks unsure how to attack on the slower surface.
No. 18 Tommy Robredo
Strengths: The marathon man has a habit of producing determined runs on dirt. Robredo, who has won 11 of his 12 career titles on clay, reached his fifth French Open quarterfinal last year in historic style. He became the second man in history to come back from two sets down to win in three consecutive Grand Slam matches, joining Henri Cochet, who did it in 1927. The 31-year-old Spaniard is one of five active men with 200 or more career clay-court victories and his desire remains undiminished. Robredo has scored top 10 wins over Federer, Stanislas Wawrinka, Tomas Berdych and Richard Gasquet in the past year. He owns a 14-4 career fifth-set record and an impressive .691 clay-court career winning percentage.
Shortcomings: Mounting mileage, advancing age and lack of a major weapon. Robredo's habit of running around his one-handed backhand to crack his favored forehand is his preferred pattern, but can leave him vulnerable against power players who can pound his weaker backhand. He lacks the jolting power to end points with a single shot that lower-ranked compatriots Nicolas Almagro and Fernando Verdasco possess. The veteran with 770 career singles matches to his credit doesn't always recovery as quickly as he once did, which can cause complications. He has suffered clay-court losses to No. 91 Leonardo Mayer and No. 84 Santiago Giraldo this season.
No. 23 Ernests Gulbis
Strengths: Physicality, a punishing serve and explosiveness from virtually anywhere on the court (and the postmatch interview). The 6-foot-3 Gulbis can deconstruct opponents with his punishing two-handed backhand, and his reconstructed forehand is a weapon when he has the time to set up for it. The 2010 Roland Garros quarterfinalist typically plays his most finely tuned tennis in big moments: he is 3-2 against top 10 opponents this season and 5-0 lifetime in ATP finals.
Shortcomings: The enemy within. Gulbis is vulnerable to mental mayhem that sabotages point construction and often compels him to overplay the drop shot when he runs out of ideas. The aggressive baseliner owns the shots to control play, but doesn't always put them together wisely. He is fifth on the ATP in aces, but 17th in service games won (84 percent). Stress can cause Gulbis to go off the grid, and anything can happen, from erupting into a racket-smashing frenzy, to kicking courtside signs, to the volatile Latvian indulging his urge to squeeze low-percentage blasts down the line.
No. 80 Dominic Thiem
Strengths: Electric groundstrokes generated by eye-popping racket-head speed, a strong tennis pedigree as the son of two coaches and protégé of Gunter Bresnik, former coach of Boris Becker, and plenty of tenacity. The youngest man in the ATP top 100 has successfully played through qualifying to reach main draws five times in six attempts this season. The 2011 French Open junior finalist's one-handed backhand demands attention, and his forehand can command rallies. Thiem is still refining the rough edges of his game, but clay is his best surface. He posted a 54-17 clay-court record with five titles on the ITF Futures circuit.
Shortcomings: Endurance and inexperience. The 20-year-old Austrian admits he must get stronger: Thiem owns a 2-13 career record when losing the first set. Thiem is working to refine his return game -- he's averaging just 16 percent return games won this season -- and sharpen his footwork to ensure he strikes on balance.