Sweltering heat gave players fits Saturday in Fort Worth, Texas during the third round of the Dean & DeLuca Invitational.

Jordan Spieth's caddie Michael Greller was forced to leave the course after 11 holes Saturday due to the overwhelming heat, which according to golfchannel.com, reached 108 degrees at Colonial Golf Course.

"(Greller) didn't tell me at all until we were walking down the 11th and he said, 'Hey, this is my last hole.' I was kind of surprised," Spieth said after Saturday's round. "I guess he had told Kelly (Kraft) at some point during the round. Kelly asked if he was okay. I thought (Michael) was acting a little strange, a little quiet. I guess it just got him early on today."

Kraft, who started his day at 2 under, played alongside Spieth during the third round.

With Greller out of the picture, Spieth's physical trainer Damon Goddard took over his bag and finished out the round.

"(Damon's) caddied for me before. Michael was really sick in Houston in 2014," Spieth said. "Damon caddied the first round. We went bogey-free, 2-under. I let Damon down today. I made my first bogey with him on the bag by 3-putting.

"It's funny, because Damon trains Kelly, too. We actually had a blast towards the end there. I mean, both of us kind of got a little off for the first few holes in the middle of the back nine there, and then we were able to grind it out and finish strong."

Spieth said he was able to stay calm and focused because he knew Greller would be fine once he received some treatment.

"I knew he was going to be OK," Spieth said. "He was running off to restrooms every time he saw one. I think it was just to get in the shade or pour water over himself or whatever it was.

"At one point he said he had stopped sweating, and he knew it was a problem and needed to do something."

Though Spieth was able to stay and finish his round — shooting a 2-under 68 to get to 4 under for the tournament — he also felt the heat, and was uncomfortable at times.

"It was tough out there because it was so hot," Spieth said. "Legs getting Jello-y. Real loose. Trying to tighten things up. I got a little lapse concentration for a few holes, just a dizziness where anybody would have where you're just kind of not fully there."