- Tiger Woods has dropped out of the top 50 of golf's world rankings
- The 35-year-old has been in the top 50 since October 1996
- Woods has spent 623 weeks as the sport's world number one during his career
- Kevin Na wins first PGA Tour event by two shots in Las Vegas
Tiger Woods, who spent a record 623 weeks as golf's number one between 1997 and 2010, has dropped out of the world's top 50 for the first time in 15 years after the latest rankings were released on Monday.
Woods, 35, is placed 51st having not won a tournament since the Australian Masters in November 2009.
The 14-time major winner first broke into the top 50 in October 1996 and remained there for 778 weeks before a persistent knee injury affected his appearances.
His form also suffered when revelations regarding his personal life in late 2009 led to a hiatus from the game as well as a divorce from his wife Elin Nordegren.
In a bid to arrest the decline Woods hired Joe LaCava as his new caddy in September following a split from former bag-man Steve Williams, the New Zealander who had been with Woods for 13 of his 14 major wins.
Woods is due to return to action at the Frys.com Open in northern California this week having not played since the PGA Championship at the Atlanta Athletic Club in August, where he missed the cut after carding 77 and 73 for the opening two rounds.
Despite his slump, Fred Couples selected Woods as one of his captain's pick for the upcoming Presidents Cup match between the U.S. and an international team in November.
Briton Luke Donald retains his position as world number one, ahead of compatriots Lee Westwood and 2011 U.S. Open champion Rory McIlroy in second and third respectively.
Steve Stricker is the top-ranked American in fourth, with Dustin Johnson in fifth and Germany's Martin Kaymer in sixth.
South Korean-born American Kevin Na has moved up to 62nd in the rankings after claiming his first US PGA Tour title as he won the Justin Timberlake Shriners Hospitals for Children Open in Las Vegas.
Na, who lives near the course, snapped a 210 tournament winless streak after carding a final round 65 to finish two shots ahead of Nick Watney to snatch the $756,000 top prize.