"In four days of golf, there's going to be a certain patch where you don't play well or you're going to have a couple of bogeys," Green said.
But there's little room for error with Clark and Byrd right behind him.
Clark had several cortisone shots two weeks ago for neck pain and is still not 100 percent, although it was tough to tell given the way he finished. Even so, he's not sure he'll go to the British Open if he qualifies.
"At least now I'm swinging freely," he said. "It's sort of not in the back of my mind whether my neck is going to hurt on every swing."
Byrd, who won the 2002 Buick Challenge and took the B.C. Open two years later, had trouble on the final two holes.
He saved par on 17 after sending his tee shot into the rough on the right, but couldn't do the same on 18. This time, he wrapped his second shot around an oak tree and into the water to the left of the green, settling for what he called a "great bogey."
"I guess everybody's game is an adventure," Byrd said. "I know Tiger's is at times. That's just golf. You hit spots and try to find a way out of it, get creative."
With the British Open next week, most top golfers skipped this event, and the Deere lost one major draw last month and another on Friday. First, Michelle Wie withdrew because of wrist injuries. Then, Masters champion Zach Johnson missed the cut.
With the 15th-ranked Johnson out, the only top 50 player left in the field was Pettersson at 46. It became clear early he wasn't going to make a move. He was 3 over for the day before finishing with a 71.
Now, the attention is on Green.
"He'll be fighting some nerves out there, I'm sure," Byrd said.