They four have been rotating in practice rounds early this week.
Jon Rahm, Tommy Fleetwood and Tyrell Hatton have emerged as the main contenders to partner Shane Lowry in the Ryder Cup.
Padraig Harrington has sent the four out in various groups over the opening couple of practice rounds.
All three are making their second appearance in the competition having featured at La Golf National in France three years ago.
Fleetwood won all his matches in his debut alongside Francesco Molinari.
Englishman Hatton was one from three in that contest with his only point coming in a fourball with Paul Casey.
World number one Jon Rahm is expecting to be Europe's talisman for the event. The Spaniard lost his opening two contests back in 2018 but then memorably defeated Tiger Woods in the singles on Sunday, becoming the last European player to win a point in the process.
You'd imagine Shane Lowry's personality will mesh well with anyone but of those options, he could be a dark horse for leading points scorer if paired with Rahm or Fleetwood.
When directly asked about pairings at his daily press conference, captain Padraig Harrington was remaining coy:
Some people play well in practice; some people don't play well in practice. You can't pick guys after three years and expect the practice rounds to determine what goes on on the Friday.
No, I'm not a great believer in judging people off a couple of relaxed days' practice.
So no, my picks are definitely based on the right partnerships, what we would have had in mind but narrowed down now. As we've got here, narrowed down even further.
I wouldn't think a lot is changing in my head and my vice captains' head between now and Friday, no.
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