Bill Haas wins AT&T National

American golfer Bill Haas has won the AT&T National by securing a three-shot victory in Maryland.

The 31-year-old from Charlotte, North Carolina, had begun Sunday in a four-way tie for the lead.

However, he finished as a convincing winner on 12 under after carding a final-round 66, which included six birdies and just a solitary bogey.

"It's so hard to win out here. It's pretty special," Haas told reporters.

"It was important I get off to a good start... the putter felt great and saved me on the back nine a couple of times."

Fellow American Roberto Castro finished second on nine under, while South Korea's DH Lee shared third place with Jason Kokrak on eight under.