Peter Jacobsen carded a 4-under 67 and is alone in second place.
"It's great to be able to play with great players and when they play well, it kind of spurs you or inspires you to play better," said Morgan. "All in all, it was a pretty good round."
Two-time U.S. Open champion Curtis Strange, Jim Thorpe, Craig Stadler, Katsuyoshi Tomori, two-time winner this season Brad Bryant and reigning Champions Tour Player of the Year Dana Quigley are tied for sixth place at 2-under 69.
On an unseasonably hot day, the temperature rose to 99 degrees on the course, a record high.