Ponte Vedra Beach - World No 1 Dustin Johnson is determined to hang on to his spot at the top of the rankings as he faces a strong challenge from as many as four rivals at The Players Championship starting here Thursday.
Johnson, 33, has held top spot for 64 weeks since winning last year's Genesis Open, but is now looking nervously over his shoulder at a crowded field of pretenders to his throne.
He has not won a tournament since his victory at the Sentry Tournament of Champions in Hawaii in January and has struggled to reproduce his best form in recent outings.
World No 2 Justin Thomas leads the chasing pack, but missed the opportunity to replace Johnson after only managing a share of 17th at the Masters before finishing tied for 21st at last week's Wells Fargo Championship.
Thomas will get another crack at claiming No 1 this week if he wins at TPC Sawgrass.
Spain's Jon Rahm, world No 4 Jordan Spieth and England's Justin Rose could also take top spot with a victory in Florida depending on various permutations.
Johnson however can prevent that outcome if he manages to finish 10th or higher.
"I don't want to lose it, so if I want to keep the number one title, I will have to play well this week," Johnson told reporters on Wednesday.
Spieth, meanwhile, who has been world No 1 on four different occasions and for a combined period of 26 weeks, is more focused on winning a first Players Championship.
"It was never a goal of mine to hold it (No 1 title) a certain length of time," Spieth said.
"It's almost like a feat, like winning a major. But now it's more like, if I remained number two and won majors and was number one for a long time and won six, I'd take the first one."