The 2004 Tennis Masters Cup was a tennis tournament played on outdoor hard courts. It was the 35th edition of the year-end singles championships, the 30th edition of the year-end doubles championships, and was part of the 2004 ATP Tour. It took place at the Westside Tennis Club in Houston, Texas, United States, from November 13 through November 21, 2004.

Roger Federer def. Lleyton Hewitt, 6–3, 6–2

Bob Bryan / Mike Bryan def. Wayne Black / Kevin Ullyett, 4–6, 7–5, 6–4, 6–2

The Barclays ATP World Tour Finals is a tennis tournament played at the end of each year, involving the top eight players in the men's tennis world rankings.

Unlike most of the other events on the men's tour, the ATP World Tour Finals is not a straightforward knock-out tournament. Eight players are divided into two groups of four, and play three round-robin matches each against the other three players in their group. From there, the two players with the best records in each group progress to the semifinals, with the winners meeting in the final to determine the champion. Winners are awarded up to 1500 rankings points.

A similar event on the women's tour is the WTA Tour Championships.

The event is the fourth evolution of a championship which began in 1970. It was originally known as the Masters Grand Prix and was part of the Grand Prix Tennis Circuit. It was organised by the International Lawn Tennis Federation (ILTF) ITF. It ran along side the competing WCT Finals the other season ending championships for the rival World Championship Tennis Tour. The Masters was a year-end showpiece event between the best players on the men's tour, but did not count for any world ranking points.

Roger Federer (German pronunciation: [ˈfeːdəʁɐ]) (born 8 August 1981) is a Swiss professional tennis player who held the ATP No. 1 position for a record 237 consecutive weeks from 2 February 2004 to 18 August 2008. Federer has occupied the #1 ranking for 285 overall weeks, one week short of the record 286 weeks held by Pete Sampras. As of 28 May 2012, he is ranked World No. 3. Federer has won a men's record 16 Grand Slam singles titles. He is one of seven male players to capture the career Grand Slam and one of three (with Andre Agassi and Rafael Nadal) to do so on three different surfaces (clay, grass, and hard courts). He is the only male player in tennis history to have reached the title match of each Grand Slam tournament at least five times and also the final at each of the nine ATP Masters 1000 Tournaments. Many sports analysts, tennis critics, and former and current players consider Federer to be the greatest tennis player of all time.

Federer has appeared in an unprecedented 23 career Grand Slam tournament finals, including a men's record ten in a row, and appeared in 18 of 19 finals from the 2005 Wimbledon Championships through the 2010 Australian Open, the lone exception being the 2008 Australian Open. He holds the record of reaching the semifinals or better of 23 consecutive Grand Slam tournaments over five and a half years, from the 2004 Wimbledon Championships through the 2010 Australian Open. At the 2012 Australian Open, he reached a record 31st consecutive Grand Slam quarterfinal. During the course of his run at the 2012 French Open in Roland Garros, Federer eclipsed Jimmy Connors long standing record of 233 match wins in Grand Slam tournaments when he defeated Adrian Ungur in a second round match.

Lleyton Glynn Hewitt ( /ˈleɪtən ˈhjuːɨt/; born 24 February 1981) is an Australian professional tennis player and former world no. 1, who has a current ATP ranking of 176.

Hewitt is the youngest male ever to be ranked no. 1 at the age of 20. His career achievements include winning the 2000 US Open men's doubles, the 2001 US Open and 2002 Wimbledon men's singles, and back-to-back Tennis Masters Cup titles (2001 and 2002). In 2005, TENNIS Magazine put Hewitt in 34th place on its list of the 40 greatest tennis players since 1965.

Hewitt might well have followed in the footsteps of his Australian rules football-playing father Glynn. Instead, he became one of the youngest winners of an Association of Tennis Professionals (ATP) tournament when, as an almost unknown youngster, he won the 1998 Next Generation Adelaide International, defeating Andre Agassi in the semifinals. Only Aaron Krickstein winning Tel Aviv in 1983 and Michael Chang winning San Francisco in 1988 were younger when claiming their first ATP title. Hewitt then left Immanuel College to concentrate on his tennis career.. He was an Australian Institute of Sport scholarship holder.

Andre Kirk Agassi ( /ˈɑːndreɪ ˈæɡəsi/; born April 29, 1970) is a retired American professional tennis player and former world no. 1. Generally considered by critics and fellow players to be one of the greatest tennis players of all time, Agassi has been called the best service returner in the history of the game. Described by the BBC upon his retirement as "perhaps the biggest worldwide star in the sport's history", Agassi's performances, along with his unorthodox apparel and attitude, have seen him cited as one of the most charismatic players in the history of the game, and credited for helping revive the popularity of tennis during the 1990s.

In singles tennis, Agassi is an eight-time Grand Slam champion who competed in 15 Grand Slam finals, and an Olympic gold medalist. A multi-surface specialist, he is the first of two male players to have achieved a singles Career Golden Slam, and one of four to have achieved a singles Career Grand Slam in the Open Era (one of seven in history). He was the first male player to win all four Grand Slams on three different surfaces (hard, clay and grass), and is the last American male to win the French Open (1999) and the Australian Open (2003). Agassi also won 17 ATP Masters Series titles, the 1990 ATP Tour World Championships, and was part of a winning Davis Cup team in 1990 and 1992. He is the only male singles player in history to have won all four Grand Slam tournaments, the Olympic gold medal and the ATP Tour World Championships: a distinction dubbed as a "Career Super Slam" by Sports Illustrated.