Roger Federer and Australian Open women's champion Serena Williams will maintain their No. 1 rankings when new ATP and WTA rankings are released on Monday.
Federer, who played Britain's Andy Murray in the Australian Open men's final on Sunday, will begin his 268th week as No. 1 and match Jimmy Connors, currently in third place, for total number of weeks as world No. 1.
Pete Sampras leads the career list with 286 weeks at No. 1, followed by Ivan Lendl with 270.
If Murray beats Federer at Melbourne Park, he could move to No. 2. Otherwise, projections have Novak Djokovic taking over No. 2, Murray third and injured Rafael Nadal dropping to No. 4.
It marks the first time that Nadal will drop out of the world's top three since his debut there in June 2005.
Nadal has been cleared of a recurrence of the knee tendinitis that sidelined him for nine weeks last year. A small muscle tear sustained at the Australian Open, where he lost in the quarter-finals to Murray, will keep him out for the next month.