What is a mud ball? Scheffler frustrated at PGA Championship

The world's best golfers began the PGA Championship on Thursday, but the main talking point coming out of Quail Hollow Club in Charlotte, United States, was a bit unexpected.

Mud balls.

World number one Scottie Scheffler spoke about the issue on Thursday, but what exactly is a mud ball?

A mud ball is actually quite self-explanatory - it's when golf balls get covered in mud and dirt during bad weather.

That might not sound too important, but it can greatly affect the flights and trajectory of balls, often causing them to spin unpredictably.

In most golf tournaments preferred lies are in place, a rule that permits players to lift, clean, and place their ball within a specified distance of its original position on closely mown areas, generally during periods of adverse weather.

However, at majors like the PGA, the introduction of preferred lies is at the discretion of tournament organisers.

Quail Hollow was hit by heavy rain on Monday and Tuesday and while most of the course was in good condition on Thursday, the 16th hole caused serious problems for the best players in the world.

World number one Scheffler and world number three Xander Schauffele picked up mud on their balls, before both pulled their approach shots to the green well wide and into the water. Both carded double bogeys.

It's unlikely either would have made that mistake under normal circumstances.

Scheffler is tied 20th in the standings on -2 after day one, while Schauffele is tied 60th on +1.

Double Open champion McIlroy is down in joint-98th on +3.

Both Scheffler and Schauffele voiced their frustrations at the PGA of America's decision not to allow 'preferred lies' on Thursday.

"It's one of those deals where it's frustrating to hit the ball in the middle of the fairway and get mud on it and have no idea where it's going to go," Scheffler said.

"I understand it's part of the game, but there's nothing more frustrating for a player. You spend your whole life trying to learn how to control a golf ball, and due to a rules decision all of a sudden you have absolutely no control over where that golf ball goes.

"But I don't make the rules. I just have to deal with the consequences of those rules. I did a good job of battling back today and not letting a bad break like that, which cost me a couple shots, get to me. Did a good job battling after that and posting a decent score."

The PGA of America decided against introducing preferred lies after weather conditions improved.

"We do not plan to play preferred lies. The playing surfaces are outstanding and are drying by the hour. We are mowing the fairways this evening," read a statement published on Wednesday evening.

"We are looking forward to an exciting opening round to the 107th PGA Championship."

It has not responded to Scheffler's comments.