The seven-times European number one, who came from five strokes behind to win the Dunhill Links Championship by a shot at St Andrews on Sunday, climbed seven spots to 16th in the official world rankings announced on Monday.
"This is very special," said the 42-year-old Scot after carding a one-under-par 71 in an error-strewn final round to clinch his 29th European Tour victory and first in 19 months.
"I was not prepared to go any lower than the 83rd in the world that I'd sunk to, and now I'm back in the top 20. That's super, that's great.
"At the start of the year, I gave myself a goal of 25th, and to beat this so far is even remarkable for me. I'm thrilled about that."
Montgomerie, who was second in the world rankings in 1996 and 1997, had slipped to a lowly 83rd by the end of 2004, a difficult year for him both on and off the course.
Only one title came his way, at the Singapore Masters in March, and his form suffered as he negotiated a painful and public divorce.
"My life changed dramatically a couple of years ago and I always said to myself the next win would be the most influential and the most important of my career," he recalled.
TWO OPTIONS
"I had to do something about it, and there were two options. I was sliding and I could let it slide, or get off one's bum and do something about it, and I did."
Europe's number one for seven years in a row from 1993, Montgomerie accepts that tour success has become increasingly difficult in recent seasons.
"The players are improving on this tour beyond belief," he said. "They see the rewards available. They see the lifestyle available. The financial reward is huge now on this tour, there's no doubting that.
"They are practising harder, they are fitter, they are tougher, they are mental. They bring all of their mental coaches and fitness instructors with them and stuff like that.
"And there's me at 42 having to compete with all of this, and it's nice that I can still do that.
"Now I'm going off to San Francisco in the knowledge that I'm still capable of doing that. And that's a real thrill, believe me."
Montgomerie is in the field for this week's WGC-American Express Championship at the Harding Park club in San Francisco, the third of four elite World Golf Championships (WGC) events played each year.
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