Munoz nearly holed a wedge on his opening hole as part of his fast start, ran in four straight birdies on the back nine and wound up with an eight-under 64 to share the lead with Jimmy Walker, Kevin Chappell and Charley Hoffman.

The Country Club of Jackson was soft from recent downpours, though the greens were running fast and true, contributing to the good scoring.

Sixteen players were at 67 or better, including Australia's Cameron Davis.

Davis had seven birdies and a bogey for a six-under 66 to complete the opening round in a share of seventh place.

Cameron Percy returned a three-under par 69 to be the next-best Australian.

Sergio Garcia, out of the top 50 in the world for the first time since 2011, made his tournament debut with a 68.

Henrik Stenson, playing in Mississippi for the first time in 10 years had a 70.

Stewart Cink opened with a 69 in his first tournament since winning the Safeway Open three weeks ago with his son on the bag, Cink's first victory since he won the Open at Turnberry in 2009.