But he then bogeyed the short eighth and McIlroy regained his grip on the final major of the season with birdies of his own at the second, third and long seventh.

Four years ago, of course, Poulter finished runner-up to another Irishman - Padraig Harrington – in The Open at Birkdale.

That earned him a Ryder Cup wild card, whereas this time he was forcing his way into Jose Maria Olazabal’s side for Chicago next month.

But it was still McIlroy, last year’s US Open champion, on course for his second major at the age of 23 years three months – four months younger than Tiger Woods was when he grabbed number two of 14 at the 1999 USPGA.

McIlroy won his first by eight shots, but this one promised the extra satisfaction of beating a chasing Woods.

Not in Washington last June because of injury, Woods was in a tie for fourth with 10 holes to go alongside Ireland’s Padraig Harrington, who with three successive birdies just before the turn was doing all he could to impress Olazabal.

As he got up and down from sand on the 10th Poulter was joined in second place by Swede Carl Pettersson, who would have been only two back but for a two-stroke penalty on the first.

He had driven just into the hazard right of the fairway and television replays showed that he brushed the grass behind the ball in drawing the club back for his second shot.

Pettersson, told about it coming off the fourth tee, showed great character by grabbing birdies at the next two holes and then another on the seventh.

The action began at 7.45am and the completion of the third round certainly did not lack for drama. It even included Tiger Woods being attacked by a prickly pear cactus.

“It got in both legs – well, left shoe, right shoe and then in my right leg,” he said of the incident right of the 15th fairway.

“It itched like hell for about a hole and then it was gone.”

At first Woods, recovering from an “horrific” front nine 40, was limping badly as he made his way down the hole, but he called for a towel from caddie Joe LaCava and carefully extracted the thorns.

McIlroy and Vijay Singh were joint leaders on the resumption and it was a see-saw battle until the latter dropped four shots in four holes and McIlroy birdied the 15th and 16th to go three clear.

He had missed putts of three and five feet before that, however, and before going off for an hour’s nap – “I didn’t get enough sleep last night” – he spoke about what lay ahead for him.

Reminded that third round leaders have not been faring too well lately - including Scott at The Open last month, of course – he also brought up what happened at Augusta last year.

McIlroy was four clear after 54 holes there and shot 80 before coming back two months later to win the US Open by eight.

“I learned a lot from The Masters and I think it will stand me in great stead this afternoon,” he said.

“That’s definitely something that I can think back to and draw on some of those memories and some of the feelings I had at Congressional.

“You realise that you might not feel the same or your anxiety level is a little bit higher. At least being in that position before I’ll know what to do again.”