More than a routine third round of 68 that took Montgomerie, who has dropped only one stroke in 54 holes, to 17 under par, his position of strength was reinforced by Westwood's strange collapse. While others birdied the first, he parred the first two and then lost his approach at the third in a bush on the right of the green.
The mistake cost Westwood a double-bogey and with two bogeys as well, it took four birdies, including two at the last two holes, to get back to level for the day. Although Westwood came from seven behind to beat Darren Clarke at the European Open last month, closing the same gap against Montgomerie might be a different matter, so his hopes of winning for the fourth time in a row - a feat last achieved by Nick Faldo ten years ago - look slim.
Instead, Monty's nearest challengers will be the American Bob May, who equalled the last to be just three behind, and Eduardo Romero, the veteran from Argentina at 12 under. Both scored 66s, Romero's beginning inauspiciously with bogeys at the first three holes but including nine birdies in the last 12 holes.
The task facing the pursuers today, however, was summed up when Romero said: "Monty is too hard to beat, but I'll be trying. He is a fantastic player. For me, he is one of the best in the world. He does everything well. I don't know why he can't win in America."
Nor does Montgomerie, but winning in Britain is another matter. Victory today would be his fourth in six British outings. The Benson and Hedges, Volvo PGA and Loch Lomond are already his, while the ones to get away were the English Open and, of course, the Open Championship. Today, Monty can also record his third successive win in Europe and sixth this season, in a span of 11 events.
The official European tour media guide states that seven wins in a year have previously been achieved by the Australian Norman von Nida in 1947 and Belgium's Flory van Donck in 1953. But in modern times, the record number of victories is six by Seve Ballesteros in 1986 and Faldo in 1992. Even then, Ballesteros only tied for the Lancome Trophy that year because darkness forced the abandonment of his play-off with Bernhard Langer. Faldo's half-dozen includes two unofficial events, the World Match Play and the World Championship, the latter not even taking place in Europe but in Jamaica.
After Paul Lawrie, on his first appearance in Britain since becoming the Open champion, missed the cut on Friday, there was better news yesterday of another Ryder Cup newcomer. Jarmo Sandelin, who only qualified for the weekend on the cut-off mark of one under, scored a six-under 66.
The big-hitting Swede, who won twice earlier in the year to book his place at Brookline, was almost back to his best, although he was self- deprecating enough to say that his round would have constituted a "bad day for Montgomerie. My target," he added, "is to improve my game to his level but I have a long way to go. Monty, I think, is in heaven."
Sandelin has never used a professional caddie prior to this week and his new partnership with Tim King, who has worked for Per-Ulrik Johansson at the Ryder Cup, is set to continue. Linda Lundberg, Sandelin's girlfriend and regular caddie, has instead being following from outside the ropes.
"With Tim working for me, it takes a lot of pressure off," Sandelin said. "He's a smart guy and has a good control of everything that is going on. I think we will probably stay together for next week and the Ryder Cup. Linda doesn't look too sad at not having to work."
"Any time that I can emulate two players such as Seve and Nick, I am very happy," said Montgomerie, who won the same British Masters title last year. "I have won six orders of merit and if I can overtake Seve with a seventh, that would be very pleasing, too. I'm in a strong position to defend and, if I get to 20 under, I'll shake the hand of anyone who gets to 21 under."