- Zach Johnson won the $1.44 million top prize at the BMW Open
- Johnson fired a final round 65 to finish on 16-under ahead of Nick Watney
- Overnight leader Jim Furyk finished third following poor final round
- Johnson can win FedEx Cup prize of $10 million with victory at Tour Championship
Zach Johnson took a step nearer the $10 million end of season prize after claiming victory at the rain-delayed BMW Championship in Chicago Monday.
The 2007 Masters champion, finished the final day with a six-under 65 to secure a two-shot victory over Nick Watney and leave him needing victory at Thursday's Tour Championship to secure the riches of the FedEx Cup.
Johnson, 37, pocketed a cool $1.44 million prize after clinching the 10th title of his career, his first since last year's John Deere Classic.
"It's extremely difficult," Johnson told reporters after being asked about the challenges of the Tour.
"The parity on the tour and in the world is second to none. I'm just thankful it has been 10 years and hopefully many more."
While there was joy for Johnson, there was yet more frustration for overnight leader Jim Fuyk.
Furyk's three-year wait for a title goes on following a final round of 71 which left him in third.
After losing out to Jason Dufner at last month's PGA Championship, Furyk missed out on a 16th career title.
The American had made history Friday by becoming just the sixth man on the PGA Tour to card a 59, but he failed to shine as Johnson and Watney accelerated.
While Furyk endured a dismal final day, Watney holed eight birdies to earn a second place finish and move up from 34th to 12th in the FedEx Cup standings.
"I knew I needed to have a good week," he told reporters.
"The guys ahead of me were ahead of me for a reason. They've been playing well all year. Luckily for me I kind of pulled everything together."
Tiger Woods finished with a round of 71 to leave him on nine under for the tournament, while Luke Donald booked his place at the Tour Championship with a 66 to qualify 29th out of 30.
Thirty players will compete at East Lake Country Club in Atlanta later this week for the chance to win the $10 million playoff bonus.