In a tournament hosted by Woods, his longtime caddy Steve Williams has continued his part-time work for Scott and their partnership paid off Thursday on the difficult Aronimink Golf Club course.
Woods said earlier in the week he will be out of action until his injured knee is completely healed and he has no idea when that would be.
Scott, a seven-time winner on the PGA Tour, was tied for the lead with Hunter Haas.
Haas is in his third stint on the tour after having spent much of his career on the Nationwide circuit. He had a career-best finish of third place in Puerto Rico earlier this season.
Dean Wilson, Joe Ogilvie, Kyle Stanley and Jhonattan Vegas Those were tied for third at 67.
Vegas made a splash on the tour this year with a win at the Bob Hope Classic and in a seven-tournament span collected $1.5 million. He then missed the cut in six out of seven events before finishing tied for 32nd and tied for 33rd in his two most recent starts.
Rickie Fowler and Vijay Singh were among those tied for seventh at 68. Defending champion Justin Rose opened with a 70.
Scott's last tour win came at the 2010 Texas Open. His biggest victory has been at the Players Championship in 2004.