Rory McIlroy goes head to head with America's top player Colt Knost in this morning's opening foursomes at the Walker Cup.
As expected McIlroy and fellow Ulsterman Jonny Caldwell will play together but they were held back to the second match of the day by Great Britain and Ireland captain Colin Dalgleish.
Playing alongside world number one ranked amateur Knost is Dustin Johnson, the current world number two.
It's a cracking match in prospect and naturally the one that will draw the biggest gallery at Royal County Down this morning.
McIlroy is first up in the afternoon singles when he plays Billy Horschel. That match is due to begin at 1.15pm.
Caldwell is one of the unlucky ones not to play in the afternoon and John Parry is the other GB&I player to miss out after lunch, although as promised, Dalgleish is playing all ten of his players on the first day as is his opposite number Buddy Marucci.
The 23-year-old Johnson is from Myrtle Beach in South Carolina and, like the Ulster pair, is playing his first Walker Cup, as is Knost.
The honour of hitting the first shot will fall to either Billy Horschel or Ricky Fowler in the first group out at 8.30am. The Americans have the honour by virtue of their win two years ago in Chicago.
They are up against the top-ranked player on the British and Irish side, Scot Lloyd Saltman who is playing alongside Welshman Rhys Davis. That game tees off at 8.45am.
In the third match at 9am English pair David Horsey and John Parry take on veteran American Trip Kuehne and Kyle Stanley.
And in the final foursome at 9.15am, Scots Jamie Moul and Danny Willett will play Webb Simpson and Jonathan Moore.
Saltman is second up for Great Britain and Ireland after lunch at 1.25pm against Ricky Fowler.
In the other matches, which start at ten minute intervals, Rhys Davies plays Dustin Johnson, Danny Willett plays Colt Knost, Llewellyn Matthews plays Jamie Lovemark, Nigel Edwards plays Kyle Stanley, Jamie Moul plays Chris Kirk and David Horsey plays Webb Simpson.
Marucci has pledged to play all ten of his players in at least three matches, with two men playing in all four games over the weekend.
Dalgleish is taking a more flexible approach and won't decide his pairings and selections for tomorrow's matches until he has seen how the first day has developed.
McIlroy has been playing well all week in practice, but he really turned up the heat yesterday as the Great Britain and Ireland side went head to head in matchplay.
The 18-year-old hammered Saltman, the only home player in the top ten of the world amateur rankings at three, and was five up by the time they completed the 18 holes. The England and Scotland team, though won the money over Ireland and Wales.
McIlroy is under enough pressure without having to be first on the tee this morning but its looks as though Marucci may have second-guessed Dalgleish by holding back Knost and Johnson to the second match.
The nerves will be jangling for whichever one of the Americans that has to strike the opening tee-shot and most of the players on both sides accept that they will never have experienced anything like it before.
Marucci expects the McIlroy factor will have a big effect.
"There will be a lot of movement out there," he said.
"If we have 10,000 people and depending on where Rory is on the course there could be 2,000 or 3,000 people watching each match with only four matches in the morning, it's going to cause some commotion.
"Although I think that in Northern Ireland the fans are very respectful and there won't be a negative response at all."
8.30am Lloyd Saltman & Rhys Davies v Billy Horschel & Rickie Fowler.
8.45am Rory McIlroy & Jonny Caldwell v Colt Knost & Dustin Johnson
9am John Parry & David Horsey v Trip Kuehne & Kyle Stanley
9.15am Jamie Moul & Danny Willett v Webb Simpson & Jonathan Moore
1.15pm Rory McIlroy v Billy Horschel
1.25pm Lloyd Saltman v Ricket Fowler
1.35pm Rhys Davies v Dustin Johnson
1.45pm Danny Willett v Colt Knost
2.00pm Llyewellyn Matthews v Jamie Lovemark
2.10pm Nigel Edwards v Kyle Stanley
2.20pm Jamie Moul v Chris Kirk
2.30pm David Horsey v Web Simpson