Caddies, with a few notable exceptions, were once the invisible men of tournament golf. But in the modern game, their prominence, bordering on celebrity status, has been highlighted by events in the Andersen Consulting Matchplay here at La Costa this week.

The latest development is Paul Lawrie's decision to sack his Irish caddie, Paddy Byrne, only minutes before setting off for what proved to be a second-round victory over Billy Mayfair on Thursday. Lawrie's coach, Adam Hunter, took over the bag, sparking controversy as to whether the British Open champion was in breach of tournament regulations.

As a former winner of the Portuguese Open, Hunter retains Category 14 status on the European Tour. But according to the tour regulations, a full member "may not caddie in a PGA European Tour-approved event".

So, should Lawrie have been disqualified before facing a third-round match yesterday against Mark Calcavecchia? Not so, according to the chief referee of the European Tour. "We gave him a special dispensation," said John Paramor, who is officiating at the tournament. This, apparently, was to paper over some cracks in the regulations for these World Golf Championship events.

Byrne is the son of Donegal-born Seamus Byrne, the wealthy owner of a major construction company in Dubai. Paddy Byrne and Lawrie met during last year's Desert Classic and a week later, Byrne caddied for him when he won in Qatar. And, of course, he was with him for his British Open triumph at Carnoustie in July.

Lawrie said: "It's just between the two of us and I hope it stays that way." Hunter, who was again on the bag for yesterday's match, said: "This (break-up) has been coming for some time." As it happens, the rule doesn't apply in the US. Meanwhile, Byrne headed back to his home in Dubai.

But the caddieshack here still retained an Irish presence in the person of Jude O'Reilly, a native of Rosses Point, who was working for Shigeki Maruyama in yesterday's match against Tiger Woods. O'Reilly's mother, Gretta, is a former lady captain of the Co Sligo club and a familiar figure in Irish women's golf and Jude spent several years on the Japanese Tour before accepting a job with Maruyama prior to this event.

This is a huge week for the so-called loopers, who can bank on a minimum of $100,000 if they bring in the winner; $50,000 as runner-up; $40,000 for third place and $30,000 for fourth. So, caddie-changes are being closely monitored.

Paul Smith from Birmingham, is happy to be back this week with Miguel Angel Jimenez, having parted with him after the Smurfit European Open 19 months ago. "It actually cost me money last year to work with Miles Tunnicliff, who lost his card," he said.

Smith went on: "While I was out of a job at the end of last season, Miguel was piling up the cash with a win in the Volvo Masters at Montecastillo and then finishing runner-up to Tiger Woods at Valderrama a week later. I gave up counting, but I reckon those two weeks would have been worth about £30,000 to me."

But he is not alone. Coming into this week, David Duval ditched his caddie Mitch Knox and took on the experienced Greg Rita who was at one stage with Greg Norman and later moved from John Daly to Scott Hoch and most recently to John Cook. "Getting a bag in a tournament like this, could be as good as a season's work in Europe," added Smith.