Analysis of information sources in references of the Wikipedia article "List of ATP number 1 ranked singles tennis players" in English language version.
He was clearly No. 1, a status he enjoyed from July 1974, for 159 straight weeks...
1997 — Ranked No. 1 every week throughout year for second time (1994)
In 1988, [Wilander] won a five-set endurance contest, breaking a six-match losing streak to Lendl. The win interrupted Lendl's three-year reign as world No. 1...
[I]n 1999 he won the French Open title, the only Major that had eluded him. He finished the year ranked No. 1 in the world for the first and only time in his career.
Nastase...finished the 1973 season No. 1 in the world.
Jim Courier became the first American since John McEnroe in 1984 to finish the year as the No. 1 tennis player in the world...(subscription required)
Rios...is the first man to earn the ranking without winning a Grand Slam tournament since Ivan Lendl in 1983.
Jimmy Connors was No. 1 for 160 straight weeks, from July 1974 to August 1977.
Edberg, the No. 1 player at the end of 1990 and 1991.
[Kuerten] is the first non-American to finish on top since the Swede Stefan Edberg in 1991.
Only five other players – Stefan Edberg (1990–91), Ivan Lendl (1985–87), John McEnroe (1981–84), Bjorn Borg (1979–80) and Jimmy Connors (1974–78) – have achieved the mighty feat.
