Northern Ireland man Graeme McDowell is five behind the leaders after firing an opening level-par 71 at the Valspar Championship in Florida.
McDowell, 39, moved to two under after two early birdies but a run of three dropped shots left him on one over before he birdied the 11th.
US player Joel Dahmen and Austria's Sepp Straka have a one-stroke lead over a group which includes Russell Knox.
Scotland Knox's round included an albatross two at the 11th.
Knox was joined on four under by England's former world number one Luke Donald and American Kevin Kisner.
England's Tyrrell Hatton and Danny Willett are sharing 11th spot on two under while Spanish stars Jon Rahm and Sergio Garcia matched McDowell's 71.
Ireland's Seamus Power is facing a battle to make the cut after an opening 74,