Barry Lane credited a salutary piece of advice from his wife as the reason for a change in fortunes after carding a 63 to go to 10 under par and within two strokes of the leader, Lee Westwood, at the Kungsangen club.
Darren Clarke shot 66 and trails five behind Westwood, but the defending champion Montgomerie's 71 left him nine strokes adrift.
Lane's career went into freefall after he made $1 million by hitting the jackpot in the first world championship five years ago.
A regular winner on the European Tour, he must have been entertaining thoughts of early retirement in the Bahamas. He had Ryder Cup and World Cup honours under his belt and his European money-list placings from 1992 read fifth, 10th, 11th and eighth.
Astonishingly, from 1996 to 1999 they were a sickening 76th, 83rd, 110th and 85th, and things have gone no better this summer as he has slipped to 118th in the league table with only £45,549 sterling to show for 16 Tour outings.
Yesterday Lane dramatically recalled the good times after a bit of a talking-to from his French wife, Stephanie.
"Stephanie travelled with me for five years and since she stopped this year I'm missing her and it's showing," Lane said. "She's been constantly telling me to `smile, enjoy yourself and don't look so grumpy,' pointing out people have paid good money to watch me play.
"She is absolutely right. I turned 40 in June and I have resolved to stop worrying about bad rounds and being too hard on myself and enjoying it for a change.
"I picked up a book on golf psychology the other day and read about a woman having a pitching lesson. The teacher asked her how many times she'd expect to hit the green if he gave her 100 balls and she said 80, so he told her to think of each shot as the first of her 80."
Lane applied his new relaxed philosophy to accumulate eight birdies, twice potting 20-yard chips.
Lane's last European victory came in Majorca in 1994. Westwood, who launched his career that year, recalls: "I played with him in the third round and finished fourth."
Westwood, who hit a three-iron 213 yards to eight inches for an eagle three at the fifth, added a 67 to his opening 63 yesterday to go 12 under par on 130.
He is hoping for a repeat of his first tour triumph in the 1996 Swedish event, recalling: "It was real Roy of the Rovers stuff, with me holing a 50-foot putt to win a sudden-death play-off."