Dustin Johnson, this week's defending champion at the BMW Championship

After a week's break, the FedEx Cup playoffs resume on Thursday with the third leg of the four-event, play-off series, the BMW Championship, at the Cog Hill Golf Club's No 4 course, Dubsdread, in Illinois.

The elite group of US PGA Tour hopefuls still chasing the $10m bonanza that will go to the eventual winner of the FedEx Cup have been whittled down to 70, with Webb Simpson now topping the rankings after his victory in the Deutsche Bank Championship a fortnight ago.

There is no cut this week so all 70 players players will have all four rounds to earn sufficient points to get among the 30 qualifiers who will go through to the finale of the play-off series in Atlanta next week - the Tour Championship at storied East Lake.

Current projections estimate that the top 21 in the current list of 70 have already done enough to ensure that they will tee off at East Lake, leaving only nine places open to the other 49 players, so the battle is on.

The lucky 21 with enough points in the bag are: Webb Simpson, Dustin Johnson, Matt Kuchar, Luke Donald, Brandt Snedeker, Jason Day, Nick Watney, Steve Stricker, Chez Reavie, Phil Mickelson, Gary Woodland, Bubba Watson, Jonathan Byrd, Vijay Singh, KJ Choi, Adam Scott, Mark Wilson, Hunter Mahan, Keegan Bradley, David Toms and Charles Howell III

Don't expect these 21 to sit back and take it easy.

They in turn will be in a fight to claim one of the top five places at Cog Hill this week for if any of those five win the Tour Championship, they'll also be sure to win the FedEx Cup and the $10 bonus fund that goes with it.

The BMW winners in the first three years of the FedEx Cup play-offs were:

2010 Dustin Johnson (-9)

2009 Robert Karlsson (-19)

2008 Camilo Villegas (-15) when the event was played at Bellerive Country Club in Missouri