The sickening incident early in the fourth quarter, in which Kopua appeared to wrench her knee after tangling with shooter Caitlin Bassett, subdued even the Australian camp as their excitement at wrapping up the Constellation Cup with another convincing win was tempered by the sadness at seeing their much-respected rival go down in such a way.
The early medical assessment revealed Kopua had dislocated her kneecap with the possibility there may be further ligament damage, but it could be a couple of days before an official diagnosis is confirmed.
While the Ferns, who have battled the entire series, grapple with the loss of their inspirational captain, the high-flying Diamonds head into Wednesday's final test in Auckland seeking further improvement from last night's emphatic 47-34 win.
The Constellation Cup may be safely tucked away in the trophy cabinet for another year, but the Australians are determined to keep on pushing.
Diamonds captain Laura Geitz said her team won't be approaching the match as an opportunity to build further depth in the side - their key focus is securing a 4-0 series whitewash.
"This current group of players don't expect anything less than a win. We have very high standards of ourselves and that's what is driving this success of the group at the moment so I think the minute we shift that objective we're losing sight of where we want to be as a team," said Geitz.
"We want to be an extremely successful generation of Australian netballers and it is just a wonderful thing to be a part of."
Whilst the Diamonds' stunning 17-goal win in the opening test in Invercargill was built on their fast, free-slowing attack, last night's equally impressive 47-34 win was the result of a gritty defensive effort.
Seeking to atone for what they saw as a lacklustre effort in the second test in Melbourne despite the final score still being a healthy 49-40, the Australian side ramped up the through-court defensive pressure on the Ferns in Sydney last night.
Under the relentless man-on defence and suffocating hands-over pressure, the Ferns struggled to find a way into their shooting circle, as was reflected in their low shooting volume.
"To keep the Ferns to just 34 goals is outstanding," said Geitz.
"It felt like the ball was taking a long time to get down to Latu and that is just full credit to the pressure that is being applied in front of me, so the girls are doing a fantastic job of making my life easy at the back."
Putting her obvious concern for her star defender to one side, New Zealand coach Waimarama Taumaunu said her biggest disappointment of last night's test was her side's inability to capitalise on their own excellent defensive work.
Led superbly by Kopua, who produced some impressive defensive plays, the Ferns picked up 18 intercepts last night and forced several more turnovers out of the Australian team, but their conversion rate was poor.
"I was really disappointed at the number of shooting opportunities we created, particularly in the first quarter [seven]," said Taumaunu.
Asked how her side would go about trying to recover from another heavy defeat last night, Taumaunu responded: "You dig it in and you try harder, and that's exactly what we're going to do."
