Question: Who was ranked World No. 1 in double first, Robert Seguso or Tom Okker?

full_context: Document 1: 1973 WCT World Doubles – Doubles: This was the first edition of the WCT World Doubles tennis tournament. The eight highest ranking teams qualified for the event. Third seeds, Robert Lutz and Stan Smith won the tournament in straight sets in the final against Tom Okker and Marty Riessen
Document 2: 1988 Wimbledon Championships – Men's Doubles: The Men's Doubles tournament at the 1988 Wimbledon Championships was held from 20 June to 4 July 1988 on the outdoor grass courts at the All England Lawn Tennis Club in the Wimbledon district in London, England. Ken Flach and Robert Seguso successfully defended their title, defeating John Fitzgerald and Anders Järryd in the final.
Document 3: Bob Bryan: Robert Charles Bryan (born April 29, 1978) is an American male professional tennis player. He has won twenty-three Grand Slam titles: 16 in men's doubles and 7 in mixed doubles. He turned professional in 1998. With his twin brother Mike, he has been world No. 1 doubles player for much of the last several years, first achieving the top ranking in September 2003. The brothers were named ATP Team of the Decade for 2000–2009. The brothers became the second men's doubles team to complete the career golden slam at the 2012 Summer Olympics.
Document 4: Arthur Ashe: Arthur Robert Ashe Jr. (July 10, 1943 – February 6, 1993) was an American professional tennis player. He won three Grand Slam titles.
Document 5: Robert Seguso: Robert Arthur Seguso (born May 1, 1963) is a former professional tennis player from the United States. A doubles specialist, he won four Grand Slam men's doubles titles (two Wimbledon, one French Open and one US Open). He also won the men's doubles Gold Medal at the 1988 Olympic Games in Seoul, partnering Ken Flach. Seguso reached the World No. 1 doubles ranking in 1985. He won a total of 29 career doubles titles between 1984 and 1991.
Document 6: Marc Rosset: Marc Rosset (born 7 November 1970) is a former professional tennis player from Switzerland who is best remembered for winning the men's singles gold medal at the 1992 Olympic Games. He also won one Grand Slam doubles title at the French Open in 1992 partnering compatriot Jakob Hlasek.
Document 7: Thomaz Koch: Thomaz Koch (born May 11, 1945 in Porto Alegre), is a left-handed former tennis player from Brazil, who was a quarter-finalist at the French Open, Wimbledon and the U.S. National Championships.
Document 8: 1973 Dutch Open (tennis): The 1973 Dutch Open was a combined men's and women's tennis tournament staged in Hilversum, Netherlands. The men's event was part of the Grand Prix circuit and categorized in Group C. The tournament was played on outdoor clay courts and was held from 16 July to 23 July 1973. It was the 17th edition of the tournament. Tom Okker and Betty Stöve won the singles titles.
Document 9: Tomáš Šmíd: Tomáš Šmíd (born May 20, 1956 in Plzeň) is a former tennis player from Czechoslovakia, who won nine singles titles during his career. In doubles, he won fifty-four titles and was World No. 1 in doubles from December 17, 1984 to August 11, 1985. The right-hander reached his highest ATP singles ranking of World No. 11 in July 1984. Šmíd participated in 31 Davis Cup ties for Czechoslovakia from 1977–1989, posting a 20-10 record in doubles and a 22-15 record in singles.
Document 10: Tom Okker: Thomas Samuel Okker (born 22 February 1944) is a former Dutch tennis player. He was ranked among the world's top 10 singles players for seven consecutive years, 1968–74, reaching a career high of World No. 3 in 1969. He also was ranked World No. 1 in doubles in 1969.
Document 11: 1985 US Open – Men's Doubles: The Men's Doubles tournament at the US Open was held from August 27 to September 8, 1985, on the outdoor hard courts at the USTA National Tennis Center in New York City, United States. Ken Flach and Robert Seguso won the title, defeating Henri Leconte and Yannick Noah in the final.
Document 12: Boris Becker: Boris Franz Becker (] ; born 22 November 1967) is a German former world No. 1 professional tennis player. He was successful from the start of his career, winning the first of his six major singles titles aged 17. He also won five year-end championships, 13 Masters Series titles, and an Olympic gold medal in doubles. "Tennis" magazine ranked him the 11th best male player of the period 1965–2005.
Document 13: Thomas Emmrich: Thomas Emmrich (born 21 July 1953) is a former tennis player for East Germany. Between 1970 and 1988, Emmrich won 47 German Democratic Republic (GDR) titles (16 singles and 31 in the doubles and mixed). Unfortunately, he entered the tennis scene after the GDR had decided to promote only those sports which were relevant for the Olympics’ medals table. Thus, he was barred from international competitions outside the Eastern bloc countries and had to keep the status as an amateur. However, he gained some points at an ATP tournament in Sofia as GDR functionaries had not noticed that it had become part of the ATP tour. After this tournament, the ATP ranked him number 482—the only entry of a GDR tennis player in the ATP rankings.
Document 14: Ken Flach: Kenneth Eliot Flach (born May 24, 1963) is a former professional tennis player from the United States. A doubles specialist, he won 4 Grand Slam men's doubles titles (2 Wimbledon and 2 US Open), and 2 Grand Slam mixed doubles titles (1 Wimbledon and 1 French Open). He also won the men's doubles Gold Medal at the 1988 Olympic Games in Seoul, partnering Robert Seguso. Flach reached the World No. 1 doubles ranking in 1985.
Document 15: 1987 Wimbledon Championships – Men's Doubles: Ken Flach and Robert Seguso defeated Sergio Casal and Emilio Sánchez 3-6, 6-7(6), 7-6(3), 6-1, 6-4 in the final to win the Gentlemen's Doubles title at the 1987 Wimbledon Championships.
ground_truth: Thomas Samuel Okker