AUGUSTA, Ga. -- As the plot thickens, the soap opera known as "The Big Four" just keeps getting edgier.
It wasn't their golf games -- though both top players were on the leaderboard come Friday evening -- but rather a tiff during the completion of their first round that offered the day's juiciest story.
Singh, playing in the group behind Mickelson, complained to rules officials that the defending Masters champion was leaving large spike marks in the greens.
"On the 13th hole, two officials approached me at two different times," Mickelson said in a statement after his round. "They were sent by Vijay to check my spikes because he felt they were unduly damaging the greens. If that is the case, I am very apologetic and will make every effort to tap down what spike marks I may make in the future.
"However, I was extremely distracted and would have appreciated if it would have been handled differently or after the round."
Mickelson proceeded to make par on the 13th hole, then bogeyed 14 and made par on his final four holes.
While his momentum was stopped on the course, the feud certainly wasn't.
"After sitting in the locker for a while, I heard Vijay talking to other players about it and I confronted him," Mickelson said. "He expressed his concerns. I expressed my disappointment with the way it was handled. I believe everything is fine now."
Perhaps fine wouldn't best describe the relationship between Mickelson and Singh, but there are no issues as far as the tournament officials are concerned.
"There was some spike that apparently tore up some grass, and Phil was the one that got blamed," said Will Nicholson, chair of Augusta National's competition committee. "One of our officials talked to Phil to see if there was a burr on the side of one of his spikes. He very generously, as you know he would, said he would change them when he got in if there was a problem. There wasn't."
Singh was unavailable for comment after his round.
According to the Associated Press, Callaway Golf spokesman Larry Dorman said Mickelson changed to eight-millimeter spikes sometime before The Players Championship, which
was held two weeks ago. He had been using six-millimeter spikes.
Professional golfers often use metal spikes and there is no USGA rule about how long those spikes can be.
All this could set up a fascinating weekend, where it's conceivable these two players could be paired together in the final round. Currently, Singh owns sole possession of fourth place at 4 under, while Mickelson is tied for seventh two strokes back.
This episode comes just three weeks after tour player Tom Pernice, a friend of Singh, reportedly asked that Bay Hill Invitational officials check the coefficient of restitution -- or spring-like effect -- of Woods' driver. The club was found to be well within the legal limits on tour.
Mickelson and Woods have had their public exchanges as well. Two years ago, Mickelson was quoted in Golf Magazine as saying Tiger plays with "inferior equipment," a comment Woods didn't take lightly.
"He hates that I can fly it past him now," Mickelson said. "Tiger is the only player who is good enough to overcome the equipment he's stuck with."
"I really don't worry about other players or what they think," Woods countered. "The real measuring stick on the PGA Tour is how much you win, and that is what drives me to compete at such a high level."
The two Americans were paired together at last year's Ryder Cup and lost both matches they played.
Singh is currently ranked No. 1 in the world, with Woods a close second and Mickelson in fourth.
And what of the other member of the Big Four, the one keeping his name out of the gossip pages?
That's Ernie Els, the only one to never publicly feud with his fellow elite players. After all, they don't call him the Big Easy for nothing.
Jason Sobel is ESPN.com's golf editor. He can be reached at Jason.Sobel@espn3.com