Ryan Palmer sizzled with a nine-under 64 to join fellow American Harris English in a share of the lead after the third round of the Sentry Tournament of Champions in Hawaii on Saturday.
Starting the day two strokes behind overnight leader English, Palmer picked up three shots in a flawless front nine, before charging home by birdieng six of his last seven holes to go to the clubhouse at 21-under par.
English made a solid fist of defending his overnight lead in a bogey-free round, with three front-nine birdies followed by four more coming home.
Another American, Collin Morikawa, carded an eight-under 65 to sit one stroke away in third place, two shots ahead of compatriot Daniel Berger, who completed a 67 to be 18-under.
Sungjae Im of South Korea shared fifth spot with America's Justin Thomas at 17-under, while Dustin Johnson, Xander Schauffele and Spaniards Jon Rahm and Sergio Garcia were at 14-under.
Scotland's Martin Laird, the only Briton in the 42-person field, birdied three of his last five holes to card a five-under 68 and join a tie for 16th place at 13-under, eight shots off the pace.
