Thomas' usual caddy felt light-headed during the back nine of Saturday's third round at the Memorial Tournament and had to withdraw.
During the third round at the Memorial Open on Saturday, Justin Thomas' caddy, Jimmy Johnson, left on the back nine after falling ill.
"Jimmy just wasn't feeling well," Thomas said, per ESPN's Mike Wells. "He was feeling dizzy. I mean, I can tell he was light-headed and just didn't have a lot of energy. I mean, I told him on 12 that if he needed to leave, he needed to leave. Just to make sure that he's OK versus both of us worrying about it out there, and I hit my tee shot and I came out and Jimmy was gone and my dad was there."
Johnson was replaced by Thomas' father, Mike, who has caddied for Justin before. Mike also serves as his son's swing coach. Thomas did not have an update on Johnson's status after the round was completed.
Thomas was 1-over when Johnson left and finished with a 3-over 75.
Mike Thomas last caddied for Justin at Kapula in 2018. That time, Johnson was out of commission dealing with a foot injury.
"Yeah, it sucks, because I really was playing well," Thomas said, per Golf Channel's Ryan Lavner. "I just made a bad double (on 16) and had a rough finish. But I didn't make those bogeys because my dad was caddying; it was just poor execution. In a day, nobody will remember it. But right now, yeah, it's a bummer."