It earned him a one-shot lead over Ireland's Padraig Harrington and a two-stroke advantage over Nuneaton's Steve Webster and US PGA champion Vijay Singh, the Fijian taking an "air" shot in a late collapse.
And, more importantly, 35-year-old Scot Montgomerie now has a comfortable cushion over money-list rivals Lee Westwood and Darren Clarke. Montgomerie held his nerve superbly after a 35-minute delay when an 83-year-old spectator collapsed and died on the course following a heart attack.
Montgomerie posted four straight birdies for an inward half of 32 while Singh dropped his first shots of the tournament in a surprising climax to the round. He missed the 17th green and proceeded to miss the ball completely with his chip, the club sliding straight under the ball. Another chip and two putts added up to a double-bogey six and another bogey came at the last when he found water off the tee, and he had to settle for a 69.
Montgomerie was not resting on his laurels however and headed for the practice ground again knowing he would need another similar round today.
"I had to be patient because not much happened between the third and 12th but the big thing for me is not dropping any shots," Montgomerie said.
"I'll be out on the range for a while again, I owe it to myself to give myself the best chance possible. I'll have to go out tomorrow and perform."
Westwood, pounds 22,000 ahead of Montgomerie in the current standings, endured a frustrating afternoon with just one birdie and an eagle and three dropped shots.
His level par 72 left him six behind his Ryder Cup colleague and just one better than Clarke who fired a third round 67 to get back into contention.
Ulsterman Clarke, second in the Order of Merit, was still not entirely happy however after three dropped shots, saying: "I get into position and keep making mistakes.
"I was four under after five and on for a good score and then I hit a brick wall. It's very irritating to say the least. I'm making silly mistakes at the wrong hole at the wrong time. I can't put my finger on why.
"I'm not feeling any pressure because of the Order of Merit but because of how solid my game is and to throw shots away is so frustrating. There's a 62 out there for somebody."
Australian veteran Rodger Davis almost beat Clarke to the punch with a third-round course-record 63 to stand just three off the pace, his best performance for five years.
"I don't know where that came from," admitted the 47-year-old, the oldest player in the field. "I haven't played like that since 1993. It was like the old me, picture the target, the caddie gives me the yardage and I ripped straight at it. I was in such a good frame of mind."Reuse content