That wasn't the only new entry in the Masters record book.
Gary Woodland matched the lowest score ever on the front nine with a 6-under 30, and actually got his score to 7 under on the day with another birdie at the 10th. But the 29-year-old American couldn't keep it going through Amen Corner, where a bogey at the 11th and a double-bogey on 12 stifled his momentum.
Woodland struggled down the stretch and settled for a 69, which left him with an even-par 216 for the tournament and seven strokes off Watson's 36-hole pace.
Watson started the third round with just his third bogey of the tournament, but he bounced back with an eagle 3 at the second after leaving his approach just 5 feet from the flag. That pushed him to 8 under, four shots ahead of his playing partner, Australia's John Senden, and 20-year-old American Jordan Spieth, who kept up the strong play in his Augusta debut with a birdie at No. 3.
Watson, looking to win his second Masters in three years, posted two rounds in the 60s for a 7-under 137 total at the midway point, good enough for the largest 36-hole advantage since Chad Campbell also went to the weekend up by three shots in 2006.
Defending champion Adam Scott was among the group four shots back after Friday, joined by Thomas Bjorn of Denmark and Jonas Blixt of Sweden.
Ricky Fowler was another player taking advantage of the prime scoring conditions, standing 5 under on the day with two holes left to play.
Early on, the patrons were roaring for Woodland, who became the first player since Phil Mickelson in the final round of the 2009 tournament to shoot 30 on the first nine holes. The only others to do it were K.J. Choi in 2004, Greg Norman in 1988 and Johnny Miller in 1975.