He said he failed to adjust to the slower greens after the rain. "I missed puts at six, seven, eight, and nine and they were all on the low side, not quite hard enough."
Williamson closed his round by making birdie on the 17th and 18th holes while playing into a 25-mile-per-hour wind, with gusts at more than 35 miles per hour.
"Obviously, I drove it well," Williamson said. "I mean, you cannot play a day like today out of the rough."
LPGA -- Rookie In-Kyung Kim shot a 5-under 67 to join South Korean compatriot Mi Hyun Kim (68) atop the leaderboard at 7-under 137 after two rounds of the Wegmans LPGA in Pittsford, N.Y.
European -- Niclas Fasth took over the lead in the BMW International in Munich with a 65 that put him two shots ahead of Peter Hanson (66) at 12 under par.
Northeast Amateur -- Billy Horschel shot a 3-over 72 in high wind to retain his lead after the third round at Wannamoisett Country Club in Rumford, R.I. Horschel, an All-American from the University of Florida, is at 6-under 201 and leads by two over Kevin Chappell (67) of UCLA.
Tiger Woods will miss next week's Buick Open to be with his wife, Elin, and newborn daughter, who was born Monday but was expected in July. The Buick Open, in Grand Blanc, Mich., is usually in August.
Former British Open champion David Duval pulled out of next month's championship at Carnoustie "as a result of personal family matters," Royal & Ancient Club officials said. Duval has played sparingly this year because his wife, Susie, is having a difficult pregnancy with their second child.
