Twelve two-man teams are battling for the championship this week at the Gold Course of the Tiburon Golf Club and Friday's play was conducted in the alternate-shot format, the most difficult of the three used for the tournament.
Sean O'Hair and Kenny Perry teamed to shoot a 64 to stand alone in second place. There was a third-place tie at 66 among the teams of Bud Cauley-Rickie Fowler, Jason Dufner-Vijay Singh and Charles Howell III-Rory Sabbatini.
Keegan Bradley and Brendan Steele, who won the tournament last year, were tied for sixth at 67.
The better-ball format will be used for Saturday's play and on Sunday the teams will take part in a "scramble," in which the best shot from each player will be used throughout the round. Sunday's scores should be the lowest of the week with expectations that some teams likely shooting in the 50s.