Mickelson, coming off a win last week at Pebble Beach, was at 6-under 136.
Jimmy Walker had a 66 and was at 4-under 138, along with Carl Pettersson (70) and Matt Kuchar (69), who was stung by a bee near the sixth green.
LPGA Tour
CHONBURI, Thailand - Karrie Webb had a birdie and three pars in the completion of the lightning-delayed second round of the LPGA Thailand to increase her lead to 3 strokes.
Webb finished with a 7-under 65 to reach 11 under on Siam Country Club's Pattaya Old Course. The Australian aced the 159-yard 12th hole with a 6-iron Friday and followed with a bogey and a par before play was called for the day. She also birdied the final four holes on the front nine.
European Tour
NEW DELHI - Peter Whiteford of Scotland shot a 4-under 68 to take a 2-shot lead after the second round of the Avantha Masters.
Whiteford moved to 10-under 134 at the halfway mark seeking his first European win.
Champions Tour
NAPLES, Fla. - Larry Mize shot a 10-under 62 for the first-round lead at the Ace Group Classic.