Rory McIlroy will enter next week's BMW Championship play-offs event in the US at his lowest world ranking for more than three years.
The four-time major winner has slipped from fourth to sixth in the rankings after missing the cut at the Dell Technologies Championship in Boston.
Winner Justin Thomas and Spain's Jon Rahm have both moved above McIlroy.
The last time McIlroy was ranked so low was when he occupied eighth spot before his Open Championship win in 2014.
McIlroy, 28, has played only 15 events in an injury-plagued season and plans to play three more tournaments before taking several months off to fully recover from a lingering rib injury.
However, he has slipped to 51st in the FedEx Cup standings and needs a good performance in the BMW Championship at Conway Farms in Illinois to climb into the top 30 and qualify for the Tour Championship.
McIlroy defeated Ryan Moore and Kevin Chappell in a play-off in Atlanta 12 months ago to win the overall FedEx Cup title, which landed him a £7.8m bonus.
The Northern Irishman is keen to avoid just his second full winless season since turning professional and plans to contest the pro-am format Dunhill Links Championship in Scotland with his father Gerry in early October before calling time on a frustrating campaign.