The US Open and the Australian Open.
Wimbledon, the US, Australian and French Opens are considered the most prestigeous.
Before tennis was a professional sport on amateurs played. Some of the amateurs become professionaland were barred from playing. Then tournaments were made open 2 both. Hence where the term comes from.
She was won 3 Australian Opens.
4 Australian titles
Who determines "official sports?" There is an International Racquetball Tour (IRT) and there is prize money for winning tournaments. There are also professional rankings and US Opens. If you consider Tennis to be an "official sport" then racquetball must be also.
It all depends on how far they get in the tournament.
Through mid-2012, Maria Sharapova has won 27 World Tennis Association titles and 4 Grand Slam wins (one each at Wimbledon and in the French, US, and Australian Opens). She also has 3 trophies in WTA doubles.
Greg won two majors: the 1986 and 1993 British Opens.