Rory McIlroy worryingly ended his practice round after just three holes in a potential setback to his US PGA Championship preparations.The Masters champion appeared in discomfort with his right foot on Tuesday, after revealing this week he had removed the nail on his little toe.Rory McIlroy was seen limping at the Truist Championship last weekendGettyAnd the foot issues are troubling him ahead of the PGA ChampionshipGettyIt may have been triggered by a blister that blighted his final day at the Truist Championship.“I’ve got a blister on my pinky toe on my right foot,” McIlroy said on Sunday after limping around the course.“But it’s underneath my nail. So I can’t really get to it. So it’s a little sore, but I’ll be all right.”Do it yourselfMcIlroy told reporters at his pre–tournament news conference ahead of Thursday’s US PGA Championship: “Softened it up in the shower and just ripped it off.”He followed it up by taking off his sock to reveal his self-imposed toe surgery.But it appears that his handiwork may not have solved the issue as images of McIlroy on the course at Aronimink showed him with his right shoe and sock off.The Northern Irishman had planned to practice on Tuesday afternoon however his plans were cut short on the fourth tee which subsequently saw him leave the course on a golf cart.McIlroy is set to tee off at 8:40am local (1.40pm UK time) on Thursday alongside Jon Rahm and Jordan Spieth.McIlroy previously admitted he may need to go up half a size on his golf shoes if he is to launch a credible bid to land a second major of the season.The issue could prove to be a significant roadblock in his quest for the US PGA Championship.McIlroy is a three-time PGA Championship winnerGettyIt comes after McIlroy returned to action at the Truist Championship – his first event since retaining the Masters last month.“It’s been a really good two and a half weeks of practice and getting back into playing competitively,” he said ahead of his return in Charlotte.Things didn’t go entirely to plan for McIlroy as he finished joint 19th, however, he found plenty of positives in his week’s work.“There’s still a lot that I learned about my game and that’s what I needed to do coming into this week,” McIlroy said.“I didn’t give myself a chance to win, unfortunately, but I still feel like it was a good week to see where my game was at and what I need to do to get myself into contention this week.”Despite falling away in the third round at Quail Hollow, McIlroy found his groove late on to hit a superb 67 in the final 18 holes.McIlroy took the positives from a disappointing weekend in CharlotteGetty“It was a nice way to finish the week,” he said. “I went away from Quail Hollow with quite a few positives.“I did some practice at home [on Monday] and I feel good about where my game is heading into this week.”