“It’s incredible how good he is. It’s astounding. He still gets it out there. He’s a good ball striker. He’s efficient. But by God, does he know how to play golf.”
Harrington is one of the favourites for the title after he won the Dick’s Open on Sunday for the third time in a row.
Lee Westwood makes his Senior debut but while Tiger Woods does not turn 50 until December next year, Harrington has no problem with the 15-time major winner being exempt in the Signature Events on the main tour.
“He’s earned it,” he said. “He’s earned it ten times over.”
Meanwhile, Holywood’s Tom McKibbin has a chance this week to clinch his place in The Open as two spots at Royal Troon are available via qualifying series at the Italian Open.
There’s also a spot at Troon for the winner of the European Amateur Championship in Denmark, where Royal Dublin’s Max Kennedy opened with a four-under 68 to lie a shot behind leader Preston Summerhays.