Pavin took advantage of Fallen Oak's soft greens in ideal windless conditions.
Langer had a 65, Chapman shot 67, and Daley had a 66.
Defending champion Fred Couples also had a good day, shooting a 66 to stay within striking distance at two strokes off the lead. It's a crowded leaderboard, with 14 players within three strokes of the lead.
The round was delayed for more than an hour because of afternoon thunderstorms.