It was utterly enthralling to watch as world No 1 and FedEx Cup points leader McIlroy and Woods, who ranks third in both categories, went at it hammer and tongs during yesterday's first round of the BMW Championship.
Three days after grinding out his third win of 2012 in Boston, there wasn't a hint of fatigue from McIlroy (23) as a superb 64 earned him a share of the clubhouse lead on eight-under with US Open champion Webb Simpson, Canada's Graham DeLaet and Indiana local Bo van Pelt.
Tiger shot 65, including a lovely chip-in birdie from the collar at nine, his last.
Outscored by McIlroy for only the second time in seven stroke-play confrontations, Woods said: "I was scoring but not playing particularly well. Rory, on the other hand, played beautifully, but I was very fortunate to post the score I shot," Tiger added.
While the Holywood star struck the ball and putted with sublime confidence, Woods let a chance or two go a-begging, not least at six where his 204-yard tee shot hit the hole but he then missed the five-foot birdie putt.
These two are so comfortable in each other's company that they even dined together in the clubhouse after Wednesday's Pro-Am. It's not a regular occurrence for Tiger to eat with rivals, but he seems inspired by McIlroy.
Both came out fighting on a course softened and left vulnerable by recent rain and preferred lies.
They birdied the first, Woods picking up another at the second. Yet McIlroy kept pace with him by sinking a 10-foot eagle putt on the relatively short par-five 15th. Each turned in four-under.
Graeme McDowell nobly called a two-stroke penalty against himself at nine, moments after vaulting into contention with a spectacular eagle two on his penultimate hole, the eighth, where he holed out from 154 yards.
The Portrush man brushed a loose leaf on his backswing as he played out of a greenside bunker at nine, his final hole. It was hardly discernable, even in super-slow motion but that didn't matter to McDowell, who instantly brought it to official attention.
His bogey six at nine and opening 68 did little harm to McDowell's prospects of winning a place at the 30-man Tour Championship in Atlanta the week after next. However, after a hit-and-miss 70, Padraig Harrington must find a higher gear to secure the top-five finish he needs at Crooked Stick to make it to East Lake.
Kaymer's form nosedived this year and he barely made the team for Chicago. Yet his first-round 65 at the KLM Open suggested the 10 hours' work he'd done each day during a three-week break from tournament golf paid off.
Unsure yesterday morning how he was going to perform in the company of captain Olazabal (72) and wild card Nicolas Colsaerts (70), Kaymer confessed: "I was a little concerned.
"Yet I hit a lot of fairways today, which was nice," he enthused. "Once I was able to do that, I'd a chance for birdies because my irons are solid. I can't hit it left anymore, which is good. When there's only one side you can miss it on, it feels very safe.
"If you change even little things in golf, it can make a big difference," explained Kaymer, who is paying the price for an ill-fated effort to change his ball flight from a fade to a draw for last year's US Masters.
Recent hard work also yielded a rich dividend at Hilversum yesterday for Chicago-bound Peter Hanson as the Swede shot four-under 66.
England's Graeme Storm led by two after a superlative, bogey-free 63. The only Irish to break par were Gareth Maybin and Peter Lawrie with one-under 69s, while Damien McGrane birdied 17 and 18 for a satisfying 70.
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