The American missed the cut at last week's Abu Dhabi HSBC Championship presented by EGA and has been feeling under the weather as the European Tour made the trip along the coast to Dubai.
DeChambeau revealed he actually felt the worst he had all week on Moving Day as he carded four bogeys but countered them with six birdies, including a chip-in at the 12th, before his big finish.
The 26-year-old has seven professional wins but has never successfully defended a title and heading into the final day two shots off the lead, he believes a win at Emirates Golf Club would be one of his biggest achievements.
"It would be incredible," he said. "Being under the weather and fighting through some of the stuff that happened last week and persevering this week would be a tremendous honour.
"I'm worse today. I couldn't hear anything out of my right ear until on number 13 it finally popped and that was helpful a little bit but, boy, was it a struggle out there for me on the greens today.
"That's okay, I'm going to go work on it a little bit. I didn't feel like I was putting bad, it just seemed like putts were going weird ways and ways they shouldn't. I'm going to work on that and hopefully have that ready to go for tomorrow."
The 27-year-old has moved into the top 50 on the Official World Golf Ranking since winning his maiden European Tour title at the Alfred Dunhill Links Championship last year and is enjoying being in the upper echelons of the game.
"Winning was obviously great," he said. "Being my first year it's nice to get over the hump and tick that box off and it definitely frees me up when I play.
"I think when you're a rookie you come in and there's this expectation, like you want to play well but you don't know how well you can play and hopefully win.
"It was good to get that one over the hump and it's been a good ride ever since then and hopefully many more to come.
"I think I've done a really good job this off-season preparing for the upcoming year with a lot of travel and it's great to be in this position going into Sunday."