Four players, Westwood, Rory McIlroy, Graeme McDowell and Ian Poulter look safely in Colin Montgomerie's side, but for the rest it could go to the wire. As things stand Harrington, Justin Rose and Paul Casey look favorites for the three wild cards.
With three weeks to go in the race to qualify for the European team, Dubliner Harrington is currently seventh in the World Points List and ninth in the European Points List.
The top eight in the standings after this week's USPGA Championship will all automatically qualify for the American team with captain Corey Pavin set to announce his four wild cards on September 7.
Currently the world number one Tiger Woods will need Pavin to choose him following his woeful performance at Firestone. Woods is currently ninth and needs to finish in the top eight at Whistling Straits to be assured of a place at Celtic Manor.