Jim "Bones" Mackay, Phil Mickelson's longtime caddie, was unable to complete his duties Friday at the WGC-Mexico Championship due to a stomach virus that has affected several players and caddies in the field.
Mackay tried to persevere after saying before the round that he did not feel well, but continued to have difficulty and asked off Mickelson's bag on the third hole at Club de Golf Chapultepec. He was replaced by Mickelson's brother, Tim. There was no immediate update on his condition.
Earlier in the week, The Open champion Henrik Stenson withdrew after 11 holes with a stomach virus, while Rory McIlroy coped with a bad stomach and the high altitude but played on.
Mickelson, 46, was part of a six-way tie for the first-round lead after shooting 67. He was still tied for the lead early in his round when Mackay had to leave the course.
Mackay has been Mickelson's only caddie for the entirety of the golfer's professional career and for all but one of his 42 PGA Tour victories. The first came in 1991, when Mickelson was an amateur and played college golf at Arizona State.
Until recently, Tim Mickelson was the golf coach at Arizona State. He is now a player agent and represents former ASU golfer Jon Rahm, who is in this week's field and was one of the first-round co-leaders. Rahm won the Farmers Insurance Open in January.