DeChambeau and Koepka were long-time rivals but have since mended that relationship, and the LIV Golf duo will now look to secure bragging rights for the tour as they take on the PGA Tour partnership.
World number one Scheffler has enjoyed a stellar year, winning The Masters for the second time as one of nine victories in 2024. That has tied Tiger Woods and Vijay Singh for the record of most wins in a single season.
McIlroy, meanwhile, once again fell agonisingly short in his bid to end a decade-long major drought, pipped at the US Open by DeChambeau, but he ended the year in style by sealing a sixth Race to Dubai title.
The Showdown in Las Vegas comes amid ongoing discussions to finalise a merger between the PGA Tour and LIV Golf, with stances on both sides appearing to soften.
The Showdown date and time
The match will take place tonight on Tuesday December 17, 2024.
It is expected to get underway at 6pm Eastern Time, which would be 11pm GMT in the UK.
Shadow Creek Golf Club in Las Vegas will host the contest.
The course hosted the 2018 match between Tiger Woods and Phil Mickelson, which was the first of this exhibition series of events.
The 18 holes will be split into three six-hole matchplay contests, replicating the formats of the Ryder Cup.
The first six holes will be played in the four-ball format, with that then switched to foursomes for holes seven to 12. The final six holes will be contested as two singles matches.
Where to watch The Showdown
TV channel: The event is set to be broadcast on TNT Sports, but timings for the coverage have not been confirmed.
Live stream: TNT Sports subscribers can also catch the contest live online via the Discovery+ app and website.
It has been reported that a $10million (£7.9m) prize is on the line, though that will be paid in cryptocurrency.
The event is being sponsored by Crypto.com, with the company’s chief marketing officer Steven Kalifowitz saying: “We will be the first to host a major golf tournament with the world’s top ranked players from LIV and the PGA Tour teeing off for a world’s-first purse in CRO cryptocurrency.”