Twice, Tewell holed out from the greenside bunkers. But on the final hole, he shanked his shot out of a trap and carded a bogey.
Despite the dropped shot, Tewell posted a 2-under-par 70 and has a two-shot lead at 13-under over Larry Nelson (69) and Mike McCullough (69) entering the final round of the Senior PGA Tours first major, The Countrywide Tradition.
Tewell is trying to notch his second career Senior major and his fourth career title; though, he has yet to win in 2001. On the other hand, McCullough and Nelson have each won twice this season.
Tom Wargo, the 1993 PGA Seniors champion, is in fourth place at 9-under after a 71. Hale Irwin, who has won all of the Senior majors except this one, is five shots back following a 2-under 70.
After 37 holes without a bogey, Tewell recorded three in the third round, including on the par-5 18th when he tried to reach the green in two shots. Tewells approach landed in a pothole bunker, where he shanked his third shot into the rough at the far end of the green.
At one point, Tewell led by five shots. He holed out from about 30 feet from the greenside bunker on the 7th, and then did the same for an eagle on the par-5 12th.
Full-field scores from The Tradition