Rafael Nadal of Spain celebrates after winning a point during his men's singles match against Peter Gojowczyk of Germany at the China Open tennis tournament in Beijing October 2, 2014. REUTERS/Petar Kujundzic
Nadal, who recently underwent laparoscopic appendectomy, is at the ninth place with $44.5 million. In the 2014 season, Nadal has won four titles and took home more than $6 million prize money. In June, he won his ninth French Open title. Nadal has current deals with Nike, Babolat, Mapfre, Kia Motors, Poker Stars, Mueller, and more. Reuters

There are a number of things that a tennis player does when playing in any minor or major tournaments. From unvaryingly checking the balls, bouncing the ball before a serve, or twisting the rackets before a return - these are the rituals that a tennis player is often seen doing during matches. Returning from an injury, Rafael Nadal and Andy Murray are competing in the 2014 China Open and they have some criticisms about the tennis balls being used in the Beijing tournament.

Following his win, 6-3, 6-4, over German qualifier Peter Gojowczyk on Oct. 2, Nadal said that the balls used in Beijing are so bad.

"If you throw the ball on the floor, the bounce goes everywhere," Nadal said via the New York Times. The second-seeded Spanish athlete has said that it is not a question if he wins or if he loses. He said he has played with the same quality of balls at the 2014 Rio Open, which he ultimately won. "It's just that we're competing at the top level of our sport, tennis, and the ball is an important thing."

Nadal also wasn't pleased by the organiser's decision to change the balls. He said swapping ball manufacturers possibly will result to injuries.

Murray also shared the same sentiments with Nadal's. The British athlete said that it is hard for them when the balls are changed week after week because it would mean that they would need to fine-tune their performance since the balls react in a different way.

Murray has booked his semifinals place after defeating reigning US Open champion Marin Cilic of Croatia in the quarterfinals, 6-1, 6-4. Nadal, on the other hand, will play against Slovak Martin Klizan in the quarterfinals.

According to Tennis Express, a tennis specialty retailer based in Texas, tennis balls are specifically designed for different court surfaces, such as clay, hard, or grass court surfaces. Manufacturers often include a note on the tennis ball cans that tells which type of surfaces the balls should be used on. The tennis balls are available in extra duty, regular duty, and high altitude variations. Extra duty tennis balls are the ones used for hard court surfaces. Regular duty tennis balls are used for clay or indoor court surfaces. The high-altitude tennis balls are used in high-altitude courts.

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