By Steve Keating
After letting major wins at the U.S. Open and PGA Championship slip through his fingers on the final day, Johnson carded a rock-solid two-under 69 on a brilliant late summer afternoon at Cog Hill Golf and Country Club for a total of nine-under 275.
This time it was Casey's turn to a suffer a collapse. Leading by three, the Briton watched in horror as his advantage evaporated with three successive bogeys from the 13th on the way to a 69.
(Writing by Steve Keating, Editing by Ed Osmond)