Instead, Bjorn Borg's Europe made it three wins from three since the inaugural staging in 2017.
The 35th-ranked Collins rallied back from 3-5 down in the opening set, winning a whopping nine games in a row to go up 7-5, 5-0.
Nadal said his hand was swollen and that he was pulling out of the tournament with deep regret.
The US-based star, winner of last year's US Open, was born in Osaka and it was clearly a happy homecoming for the 21-year-old who beamed and smiled her way through a dominant week on court.
Nadal overcame Canada's Milos Raonic 6-3, 7-6 (7/1) after Roger Federer edged out Nick Kyrgios in a super tie-break, leaving Europe well positioned for a third victory in as many editions over Team World.
The 23-year-old top seed won 7-5, 7-5 against the world number 119 to continue his excellent form which also saw him lose an epic US Open final to Rafael Nadal earlier this month.
The 20-time Grand Slam champion, who won his first match alongside Alexander Zverev in Friday's doubles tie, beat Australian Kyrgios 6-7 (5/7), 7-5, 10-7 to the delight of his 17,000-strong home crowd.
Top seed Osaka dispatched No. 9 seed Elise Mertens in Osaka, western Japan, to reach her first final since winning the Australian Open.
The 20-year-old came back from a set down to beat Australian Sam Stosur.
The 38-year-old Swiss delighted his home fans alongside Zverev, as the European pair saw off Shapovalov and Sock.
The two-time French Open runner-up recovered from 9-7 down in a super tie-break to win 6-4, 5-7, 13-11 against Canadian youngster Shapovalov.
The championship, which will take place from January 3-12 in the lead-up to the year's first Grand Slam, the Australian Open in Melbourne, will feature 24 nations split into six groups across Sydney, Brisbane and Perth.
The final was delayed for six hours and then interrupted twice by heavy rain in central China, before finally taking place under floodlights.
The 27-year-old Czech, the top seed, needed just 69 minutes to defeat the unseeded Croatian-born Australian and will play Petra Martic on Sunday.
Andy Murray, returning from hip surgery, will also compete, with his protected world ranking of two giving Britain entry to the tournament even though they are outside of the 24-team qualifying cut-out.