Seeking his second title defense in as many weeks, Morgan shares the 18-hole lead with Jim Thorpe, Mike McCullough, Hubert Green and Fred Gibson. All five men carded a 4-under-par 66 at The Golf Center at Kings Island in Mason, Ohio.
Morgan captured last week's Comfort Classic, when the event's final round was cancelled due to rain. Friday, Morgan posted a bogey-free 66 to make a run for a successfully two-peat repeat.
Nelson, who won two weeks in a row before taking last week off, fired an even par 70 in the first round. Just one day removed from lambasting the Grizzly course in just 58 strokes, the four-time 2000 Senior Tour winner offset three birdies with three bogeys.
After Wednesday's Pro-Am performance, Nelson was a heavy favorite to win his third consecutive event. But the 3-time PGA Tour major champion will have to make up four strokes, and pass 22 people in the process, to do so.
Leading money earner Bruce Fleisher is five shots off the first-round lead after opening in 1-over-par 71. Making his first start in three weeks, Hale Irwin is six back at 2-over-par.