Getting panicky and knowing his shoulder "was busted," Mihal assessed his dilemma in pitch darkness as he rested on a mound of mud, wondering if the ground would give way more and send him deeper into the pit.
"I was looking around, clinging to the mud pile, trying to see if there was a way out," he said. "At that point, I started yelling, "I need a ladder and a rope, and you guys need to get me out of here.""
A ladder that was hustled to the scene was too short, and Mihal's damaged shoulder crimped his ability to climb.
"At some point, I said, 'I need to get out of here. Now,'" Mihal recalled.
One of his golf partners, a real-estate agent, made his way into the hole, converted his sweater into a splint for Mihal and tied a rope around his friend, who was pulled to safety.
"I felt fortunate I didn't break both legs, or worse," Mihal said.
While disturbing, such sink-holes aren't uncommon in southwestern Illinois, where old underground mines frequently cause the earth to settle. In Mihal's case, the sinkhole's culprit was subsurface limestone that dissolves from acidic rainwater, snowmelt and carbon dioxide, eventually causing the ground to collapse, said Sam Panno, a senior geochemist with the Illinois State Geological Survey.
That region "is riddled with sinkholes," with as many as 15,000 recorded, Panno said.
The one Mihal survived has him debating whether returning to Annbriar is a long shot.
"It's a great course. I love the course," Mihal said, having played Annbriar a couple dozen times over the past decade. "But I would have a tough time probably walking down that hole again."
The 20-year-old course proclaims on its website that "each year new golfers are tested by our challenging 18 holes of golf."
There's no mention of its newest -- and most challenging -- hole.