Question: When was the first tennis major comprising the Grand Slam before the US Open first held?

Context articles: 2012 US Open – Men's singles final
1973 US Open (tennis)
Ken Rosewall
Bruno Soares
Grand Slam (tennis)
US Open (tennis)
Williams sisters
Pam Teeguarden
Australian Open
Li Na

The 2012 US Open Men's Singles final was the championship tennis match of the Men's Singles tournament at the 2012 US Open.
 In the final, Andy Murray defeated defending champion Novak Djokovic 7–6, 7–5, 2–6, 3–6, 6–2 to win the match.
 It was the equal-longest US Open men's final in history, lasting 4 hours and 54 minutes (equalling the 1988 US Open final played by Ivan Lendl and Mats Wilander), and the equal second-longest men's final in the Open era, only behind the 2012 Australian Open final.
 By winning the 2012 US Open, Murray became the first British man since Fred Perry in 1936 to win a Grand Slam singles title, and the first British man in the Open Era to do so.
 The match is a significant part of the rivalry between the two players.
 This match also marked a milestone for Murray, as it was his 100th match win at a grand slam tournament.
The 1973 US Open was a tennis tournament that took place on the outdoor grass courts at the Forest Hills, Queens in New York, United States.
 The tournament ran from 27 August until 9 September.
 It was the 93rd staging of the US Open, and the fourth Grand Slam tennis event of 1973.
 It was the first year the boy's championship was held.
 The 1973 US Open was the first Grand Slam offering equal prize money to both men and women.
Kenneth Robert Rosewall {'1': ", '2': ", '3': 'AM, MBE', '4': "} (born 2 November 1934) is a former world top-ranking amateur and professional tennis player from Australia.
 He won a record 23 tennis Majors including 8 Grand Slam singles titles and before the Open Era a record 15 Pro Slam titles and a record 35 Major finals overall.
 He won the Pro Grand Slam in 1963.
 Rosewall won 9 slams in doubles with a career double grand slam.
 He is considered to be one of the greatest tennis players of all time.
 He had a renowned backhand and enjoyed a long career at the highest levels from the early 1950s to the early 1970s.
 Rosewall was one of the two best male players for about nine years and was the World No. 1 player for a number of years in the early 1960s.
 He was ranked among the top 20 players, amateur or professional, every year from 1952 through 1977.
 Rosewall is the only player to have simultaneously held Pro Grand Slam titles on three different surfaces (1962–1963).
 At the 1971 Australian Open he became the first male player during the open era to win a Grand Slam tournament without dropping a set.
Bruno Fraga Soares (] ; born February 27, 1982, in Belo Horizonte) is a professional tennis player from Brazil.
 His highest singles ranking on the ATP Tour is World No. 221, which he reached in March 2004.
 Primarily a doubles specialist, his career-high doubles ranking is World No. 2, which he achieved in October 2016.
 After a few efforts, including a final in the 2012 US Open and the semifinals of the 2008 and 2013 French Opens, Soares finally won his first Grand Slam title at the 2016 Australian Open, partnering Jamie Murray and then followed that up with a second men's doubles title at the 2016 US Open.
 He has also won three Grand Slam titles in Mixed Doubles, two at the US Open, in 2012 and 2014, and one at the Australian Open in 2016.
 He was the third Brazilian tennis player to achieve this, after Maria Bueno and Thomaz Koch.
The Grand Slam tournaments, also called majors, are the four most important annual tennis events.
 They offer the most ranking points, prize money, public and media attention, the greatest strength and size of field, and greater number of "best of" sets for men.
 The Grand Slam itinerary consists of the Australian Open in mid January, the French Open in May and June, Wimbledon in July, and the US Open in August and September.
 Each tournament is played over a period of two weeks.
 The Australian and United States tournaments are played on hard courts, the French on clay, and Wimbledon on grass.
 Wimbledon is the oldest, founded in 1877, followed by the US in 1881, the French in 1891, and the Australian in 1905.
 However, of these four, only Wimbledon was a major before 1924–25, when all four became designated Grand Slam tournaments.
 Skipping Grand Slam tournaments—especially the Australian Open because of the remoteness, the inconvenient dates (around Christmas and New Year's Day) and the low prize money—was not unusual before 1982, which was the start of the norm of counting Grand Slam titles.
The United States Open Tennis Championships is a hard court tennis tournament.
 The tournament is the modern version of one of the oldest tennis championships in the world, the U.S. National Championship, for which men's singles was first contested in 1881.
 Since 1987, the US Open has been chronologically the fourth and final tennis major comprising the Grand Slam each year; the other three, in chronological order, are the Australian Open, the French Open and Wimbledon.
The Williams sisters are two professional American tennis players: Venus Williams (b. 1980), a seven-time Grand Slam title winner (singles), and Serena Williams (b. 1981), twenty-three-time Grand Slam title winner (singles), both of whom were coached from an early age by their parents Richard Williams and Oracene Price.
 There is a noted professional rivalry between them – between the 2001 US Open and the 2017 Australian Open tournaments, they met in nine Grand Slam singles finals.
 They became the first two players, female or male, to play in 4 consecutive grand slam singles finals from the 2002 French Open to the 2003 Australian Open; Serena famously won all 4 to complete the first of two "Serena Slams".
 Between 2000 and 2016, a 17-year span, they collectively won 12 Wimbledon singles titles (Venus won 5 and Serena won 7).
 By winning the 2001 Australian Open women's doubles title, they became the 5th pair to complete the Career Doubles Grand Slam and the only pair to complete the Career Doubles Golden Slam.
 At the time, Venus and Serena were only 20 and 19 years old, respectively.
 Since then they have gone on to add another two Olympic gold medals in the 2008 Beijing Olympics and the 2012 London Olympics.
 Nearly a decade later, the duo would go on to win 4 consecutive grand slam doubles titles from 2009 Wimbledon through 2010 Roland Garros, which would catapult them to co-No.
 1 doubles players on 7 June 2010.
 Two weeks later, on 21 June 2010, Serena would hold the No. 1 singles ranking and Venus would be right behind her at No. 2 in singles.
 Their most recent grand slam doubles titles came at the 2012 Wimbledon & 2016 Wimbledon events.
 They remain very close, often watching each other's matches in support, even after one of them has been knocked out of a tournament.
Pam Teeguarden (born April 17, 1951) is a former American professional tennis player in the 1970s and 1980s, ranked in the top 20 from 1970–1975, according to "John Dolan's Women's Tennis Ultimate Guide", prior to computer rankings.
 She won two Grand Slam Doubles Titles and was a quarter finalist in singles at the U.S. Open and The French Open.
 Her father Jerry, a well known coach, helped Margaret Court win the coveted Grand Slam (all four Grand Slam titles in one year) in 1970 and Virginia Wade to her 1977 Wimbledon triumph.
 Teeguarden was voted the "Most Watchable Player" based on play and appearance by a group of Madison Avenue advertising executives or "Mad Men" while playing at the US Open.
 Teeguarden played in 19 consecutive US Opens, holding the record until Chris Evert played in 20.
 She wore the first all black outfit in the history of tennis in 1975 at The Bridgestone Doubles Championships in Tokyo, starting a trend that is still popular today.
 Teeguarden was the first woman tennis player signed by Nike.
 She played on the victorious Los Angeles Strings Team Tennis team in 1981 and won the Team Tennis Mixed Doubles Division with Tom Gullikson in 1977; they were also runners-up in the league that year.
The Australian Open is a major tennis tournament held annually over the last fortnight of January in Melbourne, Australia.
 First held in 1905, the tournament is chronologically the first of the four Grand Slam tennis events of the year – the other three being the French Open, Wimbledon and the US Open.
 It features men's and women's singles; men's, women's and mixed doubles and junior's championships; as well as wheelchair, legends and exhibition events.
 Prior to 1988 the tournament had been played on grass courts, but since then two types of hardcourt surfaces have been used at Melbourne Park – green coloured Rebound Ace up to 2007 and, afterwards, blue Plexicushion.
Li Na (; ; born 26 February 1982) is a retired Chinese professional tennis player, who achieved a career-high WTA-ranking of world No. 2 on 17 February 2014.
 Over the course of her career, Li won seven WTA singles titles and two Grand Slam singles titles at the 2011 French Open and 2014 Australian Open.
 Li's rise to prominence came after those victories, which made her the first and only Grand Slam singles champion from East Asia and Asia as a whole.
 Prior to this, she had already become the first player representing an East Asian and Asian country to appear in a Grand Slam singles final, a milestone she achieved at the 2011 Australian Open.
 Li was also the runner-up at the 2013 Australian Open and 2013 WTA Tour Championships, a three-time quarterfinalist at Wimbledon and a semifinalist at the 2008 Beijing Olympic Games and 2013 US Open.
 Among her other most notable accolades, she was the first Chinese player to win a WTA tour title at the Guangzhou International Women's Open in 2004, the first to reach a Grand Slam singles quarterfinal at the 2006 Wimbledon Championships, and the first to break into the world's top 10.
 Her feats have sparked a major population growth of tennis players in East Asia, earning her the reputation as the region's tennis pioneer and trailblazer.