The greatest debate in golf is not about the Grand Slam, it's not even about champions. In fact, it's about someone who isn't a champion, an under-achiever if you will. Specifically, it is about who it is that is the greatest player never to have won a major.

It's the tag that nobody wants, and, once acquired, it's the tag that is the hardest of all to shed.

Is it Phil? Or is it Monty? Or, we could ask, is it someone else? One of the new breed, perhaps. Sergio? On a grey old Scottish day, we got the answer that the more things change, the more they remain the same.

Yesterday, with the green bucket seats in the grandstands around the 18th green full to over-flowing, and within an hour of each other, the two men who have really dominated the great debate finished their second rounds in the 131st Open championship. Colin Montgomerie, holder of the mantle for much of the past decade, rolled in a 12-footer for a birdie and a course record 64, while, some 38 minutes later, Phil Mickelson, to whom the mantle had apparently been passed, knocked in a par putt for a 76.

For many, Montgomerie remains the man who has suffered the greater injustice. He lost out in two major play-offs - to Ernie Els in the 1994 US Open and to Steve Elkington in the 1995 US PGA - and until he produced his wondrous round yesterday, there were many who felt that his time was in the past. Many believed that this winner of seven successive European Tour Order of Merits and 29 professional tournaments would never contend again, and be left alone with his memories of what might have been.

Of all the majors, the British Open has been the unkindest to Montgomerie. He had missed the cut on five of the last 10 occasions in which he played and his best finish came in 1994, when he was tied-eighth. Yet, it is a measure of how highly he is held by his peers that even Des Smyth - a professional 13 years before Montgomerie joined the paid ranks - felt obliged to add his support.

"You know," said Smyth, "Colin is such a great player. He is the best I've ever seen in Europe and I think it is a shame that he hasn't won a major. I hope he wins this week. His game deserves it. The type of golf he is capable of producing is fantastic. When he plays well, I don't know a better player."

Yesterday, Monty was in such a mood. As he walked to the first tee, with the scoreboard carrier telling the world that he was three over, the hairs on the back of his neck stood up such was the roar from the crowd.

"I was lying a hundred and odd position in the tournament and to get that sort of support was tremendous," admitted Montgomerie.

In his 45th major appearance, Montgomerie produced arguably his greatest round. Not known as a great links player, yesterday he was great. What made it all the more surprising, though, was that he had opened his championship with a first round 74 in more benign conditions.

"I can't explain it," he was to remark later. "You can't explain it. It is just one of those unexplainable things. It's golf."

One thing that he did do, however, was to change his clubs. Driving into Muirfield earlier in the week, he had spotted a giant poster by the roadside. It was of himself, advertising the new Callaway irons, clubs he didn't actually have. He went to the trailer and got them to make up a new set of Big Bertha irons and, yesterday, he used them. "They seem to be working a bit better than the old ones, so I'll keep them in," he said.

And why wouldn't he? In the second round, and in the sort of dank conditions that does a bad back no good whatsoever, Montgomerie contrived to shoot a course record. On the first he hit a three-iron approach to 20 feet, and holed the birdie putt. It was the perfect start. His round was to feature four more birdies and an eagle, and no dropped shots, which pleased him more than anything.

The eagle came on the fifth, a par five of 560 yards, where his three-wood approach finished 25 feet from the pin and he holed the putt with that belly putter he has come to love. "I'm always a great advocate of saying that you can only lose it in the first round, that you can never win it," said Montgomerie, "but I was in a very strong case of losing it."

And then, using his own kind of weird logic, he added: "If you add these two scores together, all I have is two rounds of 69, four-under. That's where I am at right now. But it is exactly where I want to be. I want to keep the momentum going. I know I can win. I've never been frightened of winning here."

As for Mickelson, his time - if ever - appears to be in the future. "I don't want to say I am out of it yet," he said, "but my play has put me in an unfortunate position."