Golf, especially the professional game, can be a constant puzzle. Yesterday, on the sort of pet day that visits the Oxfordshire as frequently as a total eclipse, players contrived to shoot the lights out in the Benson and Hedges International Open and still sought for greater perfection.

Colin Montgomerie was the classic example. "About eight and a half out of 10," reckoned the Scot when quizzed about his game. He didn't miss a fairway all day and failed to find only one green in regulation (and that, the first, by a matter of inches) on the way to a second round 66 for 10-under-par 134. That leaves him one shot behind his playing partner Per-Ulrik Johansson, who shot 65, at the half-way point.

Indeed, the three-ball of Montgomerie, Johansson and Paul McGinley - who shot 67 to lead the Irish challenge on five-under-par 139 - was the day's hot item. The breeze that had caressed the sprawling course in the morning vanished, a la the calm before the storm for the afternoon players, except that the predicted bad weather didn't arrive until after the last players had finished.

Those fortunate enough to play late made hay and forced the cut up to the two-under-par mark.

Johansson made most of the conditions. The Swede used his putter to good effect and included a 50-footer for eagle at the 11th in a stretch that had him six under for five holes.

"Not only would I bleach my hair like him, I'd dye it raw blue and put a white cross in it if it meant I could putt like him," joked Montgomerie of Johansson's hot putting streak. Ironically, Johansson conceded: "I haven't been putting well of late."

Still, the Irish part of the triumvirate caught the bug after bogeying the first. "It was great to be in a three-ball like that," admitted McGinley. The trio were a combined 18-under-par and McGinley added: "For some reason I always seem to play well alongside Monty. I played for the first two rounds with him in Dubai and finished third. It wasn't my A-game today, but I did play very solid."

McGinley was one of four Irish survivors to make the cut with Eamon Darcy consolidating his top-five finish in France last week by finishing birdie-birdie for a 68 and a midway total of four-under-par 140. Padraig Harrington shot 71 for 141 and Darren Clarke a 71 for 141.

However, four three-putts in his round proved extremely costly for John McHenry and he missed out by two shots. Des Smyth, like McHenry, finished on level par 144, while Philip Walton was six shots adrift.

Overall, though, the scoring was quite remarkable. The moves made by the likes of Jose Maria Olazabal, who was playing with Clarke, in the tougher morning conditions were overtaken by what happened later in the day.

The US Masters champion shot a super 67 to jump to seven-under-par to share the tournament lead at that stage. It wasn't to be for too long, however, as the later starters cut loose.

One of Olazabal's birdies, at the fourth (his 13th), defied all logic as he drove into a bunker, failed to hit his seven-iron recovery sufficiently well and finished in the giant Sahara bunker that blights the fairway. But then with 226 yards to the pin hit a three-iron from the sand to 15 feet and rolled in the putt.

His playing partners Thomas Bjorn and Clarke, who had played the hole in exemplary fashion but only had a par, gave each other one of those looks and grinned.

"Typical Ollie, wasn't it," remarked Clarke later. "Once you get him in a bunker he's dangerous. That's what he does best."

Clarke, for his part, could have made a real charge. He played superbly from tee to green, but his putter was as cold as ice. "The putts just didn't drop," he remarked. He gave himself birdie opportunities virtually everywhere but converted just one - at the first, his 10th hole.

But Olazabal's move and that of Nick Faldo, who shot 69 to join the Spaniard on seven-under-par, proved less significant as the day wore on, even if the two overnight leaders didn't fully capitalise on their opportunity.

Philip Price shot 70 to lie third on his own on nine-under-par, but Miguel Angel Jimenez could only manage a 72 to stay on the seven-under-par mark.

Elsewhere, some strange and wonderful things were happening. For instance, Australian John Senden finished his round birdie-eagle-birdie-birdie to survive and, after starting with two double-bogies in his opening five holes, Ian Woosnam finished the rest of his round in six-under-par to make the cut by one shot.

However, for Justin Rose, there was to be no miracle as he missed his 19th straight cut.