Three short months ago at The Players Championship in Florida, Phil Mickelson was extolling the virtues of Five Guys Burgers, a growing chain of hamburger restaurants getting rave reviews across the United States.

“That place is so good,” drooled Mickelson, attempting his best Homer Simpson impersonation. “I can't stop going there. This will be my sixth day in a row. I grew up (in California) on In-n-Out. I thought that was the best burger until I had Five Guys. That is hands down the best burger I've ever had.”

Turns out that Lefty had bought the rights for Five Guys franchises for Orange County in southern California, deep in the heart of In-n-Out territory but the point here is that Big Phil is a burger afficionado.

Or was. On Tuesday, during his pre-tournament press conference for the US PGA Championship at Whistling Straits in Wisconsin, Mickelson revealed he had been diagnosed with psoraitc arthritis, an intensely painful medical condition where the immune system attacks a sufferer's joints and tendons.

Mickelson had been in such pain on the Sunday mornring before the US Open at Pebble Beach in June that he had been unable to walk but eight weeks later, having begun a course of treatment, he said he was back to 90 per cent.

The one remaining downside for him, though, has been that he has undertaken a radical change in diet.

“The last seven weeks, this will be the shocker,” Mickelson said, “I've actually been a vegetarian believe it or not.

“I know this is crazy, but I know, I know. No, this wasn't recommended by a doctor, I read a book and just thought maybe it will help. And if it helps my situation, I'm all for it.

“So for the last, actually eight weeks, I've been a vegetarian. Can you believe that? I mean it just, it's not really me, but it has been.”

And what about the Five Guys franchises?

“We're working on a veggie burger,” said Lefty, with a grin.