Romero's tee shot landed in a bunker, from which he pitched across the fairway and into another bunker. His next shot landed in a creek short of the green, and he needed help from fans in a nearby grandstand to find his ball.
Meanwhile, two-time champion Hale Irwin waited on the green above to attempt a short putt for a birdie that he missed.
"I knew I had to make that putt to make the cut," said Irwin, who finished 5 over, one below the cut, and was eliminated from a Champions Tour major for the first time, breaking a streak of 24 tournaments. "There's nothing good about my game right now ... I'm fed up with it."
"It would be nice to not finish in second again and come back with that beautiful trophy," Watson said. "I'm sure in the last two rounds (the course) will test us. The first two rounds did."
He won't have to worry about Doyle this year. The two-time defending champion finished 11 over after a miserable opening round before a second round at even par.
"When everybody was saying three-peat, I was saying there was a reason no one has," Doyle said. "I tried to underplay it and downplay it some, but golf's a game when you're on, you're on and you can make things happen. And when you're a little off sometimes, you just can't make them happen."
Watson said even as his body begins to falter, he's as competitive as when he began his pro career in 1971.
"I love to compete, it's fun to be in the hunt and to see if you can hit the right shots when the chips are down," he said. "That gives me a great deal of satisfaction when you can do that. And when I lose that, I won't be out here."
Divots: Irwin's last cut from any event was the 2004 PGA Championship, also played at Whistling Straits. ... Bob Ford recorded the 17th known hole-in-one in U.S. Senior history on the 166-yard, par-3 third hole using a 7-iron. ... Doyle, Gary Player and Miller Barber are the only three golfers to win back-to-back U.S. Senior Open titles in the tournament's 27 years. ... Amateurs Brady Exber, Danny Green, Marty West, Jim Knoll and George Zahringer made the cut.