Donald targets return to top
Luke Donald tees off at Wentworth on Thursday knowing a successful defence of the BMW PGA Championship will take him back to world number one.
Donald took top spot for the first time when he beat incumbent Lee Westwood in a play-off a year ago.
He stayed there until Rory McIlroy's victory at the Honda Classic in Florida in early March, and there have been four further changes between the pair since.
The 23-year-old Northern Irishman, who next month defends his US Open crown in San Francisco, is also in the field for the European Tour's flagship event.
If Donald finishes second, McIlroy would have to win to keep hold of the number one position and if McIlroy misses the halfway cut - as he did on his last start at the Players Championship two weeks ago - Donald would need to finish eighth or better.
Westwood is currently third on the rankings, but just too far back to have a chance to leaping over the other two this week.
Former Masters champion Mike Weir is a late withdrawal. The Canadian injured his lower back in the first round of the HP Byron Nelson in Texas last Thursday.
Challenge Tour graduate Danny Denison, from Leeds, comes into the field and will be making his debut in the championship five years after breaking both legs in a car crash.
The 27-year-old spent nearly two years on the sidelines before resuming his career, finishing joint runner-up in the St Omer Open last year and winning a Challenge Tour event in Denmark.
He has made only two halfway cuts in 10 starts so far this season.