But he had not given up hope of lifting the first prize – the biggest in golf – tomorrow.

The gap was six until the Scot made an 18-foot birdie putt to take the long 18th. He raised his arms in triumph and after that said: “This is not out of bounds yet – but it’s not looking good.

“I need to win three of the first seven this afternoon. If I do that and get back to two down then things could happen.”

In the other match, meanwhile, Robert Karlsson, another member of Ian Woosnam’s side at the K Club next week and trying to become the first Swede ever to reach the Match Play final, lost an early two-hole advantage to trail American Shaun Micheel by one after 16.

The 43-year-old Montgomerie, who admitted he was already “very tired” after his last-green wins over David Howell and Campbell, was unable to find his best form throughout the morning action.

He even walked off and left it to his caddie Alastair McLean to confirm to Casey that the par five 17th had been conceded before the Surrey golfer attempted his eagle putt.

Casey, making his debut in the event and with victories already over major winners Retief Goosen and Mike Weir, went ahead when Montgomerie missed the green at the short second and failed to get up and down.

Needing to take the title to go top of the European Order of Merit – it is the same for Karlsson – Casey did three-putt the third, but his birdie four on the long fourth took him aheadagain.

The Scot then had further bogeys on the sixth and eighth – he had what almost looked like a shank out of a fairway bunker on the first of those – and Casey hammered home his advantage by making birdie putts of 10 and four feet at the next two greens.

Micheel, this week’s biggest giant-killer with the scalps of Tiger Woods and world number 10 Luke Donald already under his belt, was saying the same after nine holes.

The former US PGA champion missed a four-foot putt on the first and ran up a bogey six at the fourth to fall two down.

Karlsson, like Casey a debutant in the event, bogeyed the next, chipped in at the seventh, but then had another bogey on the eighth and although he turned in 34 to Micheel’s 37 the gap was only one.

A bogey six on the 12th made it level, Micheel holed from 30 feet at the next and after he had double-bogeyed the 15th following a bad drive down the 15th he made instant amends with a 14-footer at the 16th.

The four players were already guaranteed £120,000 for their week’s work, but reaching the final was worth £400,000.

There was a body of opinion that it would be no bad thing for Europe’s chances in the Ryder Cup next week if Montgomerie, the oldest player on either team, did not have an arduous weekend.

But that was not the way he saw it, naturally.