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Heavy lies the crown, as golf's king-in-waiting Phil Mickelson discovered after making a steady-as-she-goes season debut at Torrey Pines Thursday.

Mickelson, who is looking to fill the big shoes of Tiger Woods, had barely finished signing his scorecard for an opening 2-under-par round of 70 when Robert Allenby questioned his integrity.

Mickelson is using a Ping Eye 2 wedge at the Farmers Insurance Open which is allowed under an old court decision, but many players believe goes against the spirit of new rules which prohibit grooves that allow more control of shots.

"I just believe that even if they are legal, you still shouldn't be using them," said Allenby. "Just because someone has a couple sitting in their garage somewhere or they've got them off eBay or whatever, I just don't think that's the integrity of the game."

"I think 'cheating' is not the right word to use, but it's definitely an advantage."

When told that Mickelson was one of the handful of players -- including Hunter Mahan, John Daly and Dean Wilson -- who have put the 20-year-old wedge in their bags, Allenby appeared stunned.

"Oh, he's using one this week? Well, I have no comment there. I'll be a good boy," said the Australian.

A day earlier Mickelson -- who's been critical of golf's decision to roll back grooves, saying it unnecessarily cost manufacturers millions of dollars -- defended his use of the Ping club, which he said he had in his garage from his college days in Arizona, where Ping is based.

"I feel like the Eye-2 grooves are not legal, or don't conform, but they are approved for play," Mickelson said Wednesday.

"And after talking about it to the tour and the USGA, the only thing that matters is, 'Are they approved for play?'

"So I don't feel that there's any problem if I were to play those clubs or if anybody else were. All that matters is that it is OK under the Rules of Golf."

The incident was a crash course for Mickelson about life as golf's top dog; a life lived -- as Woods knows too well -- with a bull's-eye on your back.

The left-hander found himself in a tie for 40th after the first round, a statistic which is better than it seems because he played on the much more exacting South Course.

Indeed, only five players, led by Allenby's 5-under 67, bettered Mickelson on the South Course, which hosted the 2008 U.S. Open. Scott Piercy leads the tournament after shooting an 8-under 64 on the shorter, more benign North Course.

"I don't want to upset people and say the North Course is Mickey Mouse but it is a bit Mickey Mouse," said Allenby.

Mickelson essentially acknowledged the truth in Allenby's observations.

"I'll take a couple under on the South Course," he said, "The course is playing long and it's not the easiest to go low on. I played a little more cautious today, trying to not make too many mistakes and keep myself in it because tomorrow the North Course is a course that provides an opportunity to shoot a low round."

Mickelson also alluded to a new-found approach now that the chance of reaching No. 1 for the first time presents itself with Woods out of the picture indefinitely.

"I want to work my way into the tournament," he said.

"(Jack) Nicklaus used to talk about that in majors, that he wanted to try to progress as the week went along. And I didn't want to try to come out and win the tournament on Thursday because it's just not possible.

"I wanted to try to build into it."

Perhaps not coincidentally, that's also the blueprint Woods has relied on for his entire career.

"Maybe," Mickelson said when asked if it was a different mentality from his usual gung-ho style.

"But I knew I had to change. I had to slow down because I was just so anxious for the year to start. I knew I needed to be a little more patient."

Mickelson said although he's won early in the season before, "I've also had a number of high rounds and poor finishes and missed cuts early on".

His round could've been better given he hit the hole on putts early in his round which somehow stayed out.

"He rolled the ball unbelievable," said his playing partner, Ryan Palmer, who shot 68.

"He hits some putts today that I can't believe didn't go in."

Earlier, Mahan had said that the absence of Woods might be Lefty's big break.

"I think he sees this an opportunity to step up and kind of be The Man," he said.

Palmer agreed, to a point.

"I think a lot of people are going to look to him to do that. He's going to carry the load a little bit," he said.

"Until Tiger gets back."