Watson was joined at five under for the championship by Jeff Maggert and Peter Fowler. Maggert shot a 65 and Fowler a 66 in their morning rounds.
But all the attention turned to Watson, the 65-year-old Hall of Famer heating up in the sizzling Sacramento sunshine.
Watson made four birdies and three bogeys to provide the drama at sun-drenched Del Paso Country Club in Sacaramento, where the temperature soared above 100 degrees again.
Watson is trying to become the oldest winner of the event, the oldest to win a senior major and the oldest to win on the Champions Tour.
Bubba Watson shot a three-under 67 on Friday to maintain a two-stroke lead after the second round of the
After opening with a 62 on Thursday, Watson had three birdies in a bogey-free morning round to enter weekend play at 11 under par. The two-time
Watson won the 2010 tournament for his first
Brian Harman birdied two of his final three holes during an afternoon round of 65 to join Brian Stuard and Carl Pettersson at nine under.
Stuard, who followed an opening 64 with a 67, pulled within a shot of Watson after back-to-back birdies on 15 and 16. But he bogeyed the 17th after hitting his second shot over the green and missing an 8-foot par putt. Pettersson had a 66.
Thirty-three players were within six shots of the lead.
Mi Jung Hur birdied her final five holes to reach eight under and top the leaderboard in the
Hur completed 14 holes before play was suspended because of darkness.
Azahara Munoz birdied six of eight holes in a 6-under 65 for a share of the clubhouse lead. The Spaniard was tied with Brittany Lincicome and Anna Nordqvist at Pinnacle Country Club.
Na Yeon Choi also was 6 under through 14 holes, while Ryann O'Toole finished with a 66.
Top-ranked Inbee Park had a 69, and defending champion Stacy Lewis was 4 under with three holes left.
Spain's Rafa Cabrera-Bello shot a 5-under 67 to take a one-stroke lead after the second round of the BMW International Open in Munich.
Cabrera-Bello had a 12-under 132 total at Munich Eichenried.
England's James Morris was second after a 66.