Montgomerie is five behind the South African Retief Goosen at the half- way stage of this rain-hit tournament, but further downpours - which are forecast - could mean that only 18 of the scheduled 36 holes are possible.
It explained the Scot's disappointment at the end of a round which went from the sublime to the ridiculous. While Goosen again kept a bogey off his card in adding a 67 to his opening 64 for a hugely impressive 13 under- par-total of 131, Montgomerie's 70 for eight under included a bizarre birdie off a wooden bridge and a double- bogey where, playing off grass, he hardly moved the ball.
Montgomerie's second to the 514-yard island that is the 18th bounded over the green and bounced on to the bridge behind. Luckily for the Scot, the ball came to rest on one of the wooden planks rather than in a crack in between and from there he chipped over the edge of the water to within seven feet of the flag and made the putt.
After four other birdies, the US Open runner-up was only three behind Goosen and lying clear in second, but the world No 3 then made a mess of the 197-yard eighth. Using a six-iron he could hardly believe his eyes as it flew straight over the green and finished in dense rough. There was little change after his first attempt which only clipped the ball and the resultant five greatly increased the chances of Goosen achieving a second European Tour victory
"I should be three behind at worst," Montgomerie said. "There must have been a gust or something at the eighth. It was a disappointing way to finish, especially as we may be playing only one round tomorrow."
He is now in a tie for fourth spot, joint second being shared by Surrey's Martin Gates and the Frenchman Marc Farry on nine under, four adrift of Goosen.
The South African returned from a rain-enforced break to record three pars and then a two-putt birdie at the 18th. "I've been up at 6am each day since Monday," he said. "Now I'm going back to bed for a sleep before I watch the rugby."
Worksop's Ryder Cup hopeful Lee Westwood shot 70 to go seven under, but his disappointment at dropping two late strokes was tempered by the memory of the previous evening when he faced the possibility of disqualification.
He did not replace his ball after the television commentator and former Ryder Cup player Ken Brown trod on it, but the 24-year-old was cleared of any blame by the tournament director, David Garland.
Sandy Lyle, in his first European appearance of the season, stands at five under, while his fellow Scot Sam Torrance missed the cut after taking a quadruple bogey eight on the 15th after he put two balls in the lake.