But first up, it's Ernie Els, captain of the global squad, who made his four captain's picks on Wednesday at 8 p.m. ET.
Eight players qualified automatically - debutants Li Haotong of China, Taiwan's CT Pan and Mexico's Abraham Ancer, along with Australian newcomer Cameron Smith and his more experienced compatriots Marc Leishman and Adam Scott.
Former world No 1 Day joins fellow Australians Adam Scott, Marc Leishman and Cameron Smith in the youngest ever worldwide team, who boast only two players in the world's top 20, with the average age of the 12 players just over 29.
"I wanted good driving (and) good ball striking, but putting is very important".
"But I had to look at guys' long-term form, guys who have played well for a while". In my experience of this Cup, it comes down to pressure putting in a lot of instances. "There are numerous guys I had to call". Scott, at 17th, is the highest-ranked worldwide player.
Day owns a 5-11-4 Presidents Cup record but has had plenty of success in match play elsewhere on the PGA Tour, having compiled a 22-14-0 record and two victories (2014, 2016) in the World Golf Championships-Dell Technologies Match Play.More news: Lewis Hamilton is F1 champion and Schumacher record threat
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It will be Hadwin's second Presidents Cup appearance.
South Korea's 2019 PGA Tour Rookie of the Year Im and Chile's Niemann have been in spectacular form lately and both will make their Presidents Cup debuts.
Korea's Sungjae Im (No.11) will continue a memorable first year on the PGA Tour by making his Presidents Cup debut. The 20-year-old Chilean picked up his first win earlier this season at A Military Tribute at The Greenbrier, and had four top-10 finishes last season - including back-to-back T5s at the Travelers Championship and the Rocket Mortgage Classic.
Day had six top-10 finishes on Tour last season, and is fresh off a win at MGM Resorts The Challenge: Japan Skins - the special skins challenge in Japan last month ahead of the Zozo Championship.
The Presidents Cup has been a lopsided affair since it began in 1994, patterned after the Ryder Cup to give worldwide players from outside Europe a chance to compete in a team event.
Niemann is the sixth player from South America to qualify for the Presidents Cup, joining Carlos Franco (Paraguay/1998, 2000) Angel Cabrera (Argentina/2005, 2007, 2009, 2013), Emiliano Grillo (Argentina/2017), Jhonattan Vegas (Venezuela/2017) and Camilo Villegas (Colombia/2009).