Ryan Palmer has taken a one-shot lead after day one of the HP Byron Nelson Championship in Irving, Texas.
The American sunk six birdies as he carded a round of 64 to put him on six-under-par overall.
Australia's Marc Leishman is a shot further back with Germany's Alex Cejka, while American Scott Piercy is one of four players on four-under.
Phil Mickelson got off to a disappointing start to the tournament as he posted an even-par 70 alongside Ernie Els.
