You're not alone in thinking Federer should be at the top of this list. In this case, Federer has to settle for second place, as former Romanian professional and businessman Ion Țiriac is the richest tennis player of all time.

Originally from Transylvania, Țiriac began his professional sports career with Romania's national ice hockey team before moving to tennis in 1968. He won the 1970 French Open men's doubles with compatriot Ilie Năstase and went on to win the Davis Cup on several occasions. Despite never winning a Grand Slam singles title, Țiriac had a career-best ranking of No. 8 and amassed 22 career titles during his career.

Following his tennis career, Țiriac moved into business, where he has become one of the wealthiest athletes in history. Țiriac is the wealthiest tennis player of all time, with a diverse business portfolio that includes retail, insurance, auto leasing, and airlines.

Career Span: 1968 – 1979

Net Worth: US $1.6 billion

The all-time finest. Without a doubt, the greatest player in the history of the sport. Roger Federer has had a lot of success both on and off the field.

Federer is the richest active tennis player, with a net worth of US$900 million collected over his 23-year career. Federer has been the unquestioned monarch of the sport, holding the joint-most Grand Slam titles for male players (20).

Federer's supremacy on the court has prompted a slew of world-famous brands to work with him over the years to help him build his brand value. Federer's stellar two-decade career has seen him establish his spot as not just the best player of all time, but also one of the wealthiest players ever, thanks to brands like Rolex, Gillette, Wilson, Mercedes-Benz, Nike, and many more.

Career Span: 1998 – present*

Net Worth: US $900 million

Sponsors: Uniqlo, Nationale Suisse, Credit Suisse, On, Rolex, Lindt, Sunrise, Jura Elektroapparate, Gillette, Wilson, Barilla, Moët & Chandon, Mercedes-Benz

Novak Djokovic has established himself as a force to be reckoned with in the era of Federer and Rafa Nadal. With 20 Grand Slam championships and other prestigious records, including the Double Career Grand Slam and the Non-Calendar Year Grand Slam, as well as the record of being World No. 1 for the longest weeks (354) in tennis history, the Serbian ace will go down in history as one of the game's greats.

Novak Djokovic has promoted several products throughout his career, in addition to his on-court achievements. Djokovic is one of the most recognizable faces in tennis after over two decades on the court, and his net worth of over US$200 million places him among the richest tennis players.

Career: 2003 – present

Net Worth: US $220 million

Sponsors: Telekom Srbija, FitLine, Adidas, Sergio Tacchini, Audemars Piguet, Uniqlo, Mercedes-Benz, Seiko, ANZ, Jacob’s Creek, Orlando Wines, Lacoste, Raiffeisen Bank International, Ultimate Kronos Group

Williams' record as the best female tennis player of all time speaks for itself. Williams has been one of the most dominant powers in women's tennis in the modern era, with 23 Grand Slam titles, one less than Margaret Court's record.

Serena Williams is the active player with the most major titles in singles, doubles, and mixed doubles, and is joint-third on the list of total major titles won. Both women have cemented their names in the sport's history books after forming one of the strongest on-court combinations with her sister Venus.

With endorsement relationships with Nike, Gatorade, Wilson, Aston Martin, IBM, and Beats by Dre, among others, the younger Williams has developed her brand. Williams is the richest female tennis player of all time, with a net worth of $200 million.

Career: 1995 – present*

Net Worth: US$ 200 million

Sponsors: Puma, Nike, Wilson, Gatorade, Delta Air Lines, Aston Martin, Pepsi, Audemars Piguet, Beats by Dre, IBM, Intel, Chase Bank, Tempur, Mini, OPI Products

The King of Clay. The young man dared to question the king. Rafael Nadal holds a particular place in tennis history. With 20 Grand Slam titles, he is considered one of tennis' all-time greats.

Apart from his battle with Federer and Djokovic, Nadal holds the record for the most titles won in a single tournament (French Open – 13) and the longest single-surface victory streak (81 consecutive wins on clay).

Nadal, a youth hero, has teamed with brands such as Kia Motors, Nike, Emporio Armani, and Tommy Hilfiger, among others, bringing his net worth to a whopping US$190 million.

Career: 2001 – present

Net Worth: US $190 million

Sponsors: Kia Motors, Nike, Lanvin, Quely, Richard Mille, Emporio Armani, PokerStars, Babolat, Tommy Hilfiger

Agassi, the Punisher, a former World No. 1 and eight-time major champion, is an American legend.

Agassi began his professional career at the age of 16 in 1986 and won his first major title in 1987. He won his first Grand Slam championship, Wimbledon, in 1992, and is a four-time Australian Open champion. He is also the only player to complete the career Super Slam (career Grand Slam and Olympic gold medal) and the second to complete the career Grand Slam.

Agassi is one of the wealthiest tennis players of all time, having promoted businesses such as Adidas, Nike, DuPont, Ebel, Mountain Dew, Kia Motors, American Express, Deutsche Bank, and Jacob's Creek, among others, during his celebrated two-decade career.

Career: 1986 – 2006

Net Worth: US $175 million

Sponsors: Prince Graphite, Donnay, Adidas, Nike, Head, DuPont, Jacobs Creek, Kia Motors, Deutsche Bank, Canon, American Express, Mazda, Longines, Nintendo Wii, LVMH

Sir Andy Murray, one of Britain's best tennis players, completed the Big Four in the mid-2000s (together with Roger Federer, Rafael Nadal, and Novak Djokovic). Apart from winning three Grand Slams, Sir Andy is the only male tennis player to have won two Olympic gold medals to date.

Murray has partnered with Adidas, Head, Under Armor, Castore, Rado, and Highland Spring, among others, over the course of his career, earning him a spot on the list of the all-time richest tennis players.

Career: 2005 – present

Net Worth: US $165 million

Sponsors: Adidas, Shiatzy Chen Royal Bank of Scotland, Highland Spring, Castore, Head, Rado, Under Armour

Pistol Pete is a 14-time Grand Slam winner known for his precise and powerful serves. Sampras was and remains one of the greats, with 64 singles titles and 286 weeks at the top of the rankings. His battle with Andre Agassi was legendary, and Sampras is still regarded as the greatest serve-and-volley player in tennis history.

Sampras is certainly one of the wealthiest tennis players of all time, being one of the most successful players of his period.

Career: 1988 – 2002

Net Worth: US $150 million

Sponsors: Nike, Wilson, Pizza Hut, Dannon

Maria Sharapova, one of the most recognizable faces in tennis history, requires no introduction.

Sharapova gained international fame after her debut in 2003, achieving World No. 1 at the age of 18 in 2005. Sharapova was one of the most successful female players of her generation, winning five Grand Slams and 36 major trophies. She was a brand magnet outside of tennis, and with endorsement deals with Nike, Cole Haan, Motorola, Gatorade, Tropicana, Fred Perry, Tag Heuer, and Tiffany, among others, Sharapova is one of the wealthiest tennis players of all time.

Career: 2003 – 2020

Net Worth: US $135 million

Sponsors: Motorola, Land Rover, Canon, Tag Heuer, Tiffany, Gatorade, Tropicana, Nike, Fred Perry, René Lacoste, Head, Porsche, Cole Haan

McEnroe was one of the greatest players of his generation, despite his combative on-court conduct. He won seven Grand Slams in his career, including 77 singles victories and 78 major titles, and his 1984 season record of 82-3 is still the best single-season victory rate.

While McEnroe's on-court antics got him into controversy with match officials, they also turned him into a brand magnet. McEnroe ranks among the all-time wealthiest tennis players, having promoted brands like Nike, Mercedes, American Express, Bic, Dunlop, and Sergio Tacchini.

Career: 1979 – 1992

Net Worth: US $100 million

Sponsors: Dunlop, Sergio Tacchini, Nike, Bic Razor, American Express, Tesco, Mercedes, Heineken, Seat Altea