"Some days I just cry, and I have no idea why. It's probably just a build-up of frustration," said Kopua.
Summer rehab is nothing new for Kopua. Off-season medical procedures and injury rehabilitation became a routine part of her life long ago. She's had regular lay-offs to rest her "dodgy knees" and arthroscopic surgery to slice out rogue cartilage in each ankle - one in 2011, the other at the end of the 2013 season.
Casey Kopua is assisted by medical staff after her devastating knee injury. Photo / Getty Images
This summer has been different. It's not general wear and tear that have got her laid up, but a violent knee injury.
The Casey Cut-off has become one of the athletic defender's signature moves over her career. If you were to ask fans to single out what makes Kopua such a special player, most would favour her hunting instincts outside the circle - the way she swoops in on cross-court passes, seemingly hanging in the air for an age to pull in the intercept.
Others relish watching her get up for the aerial contest, disrupting the long-ball into the tall shooters. But of all the tricks Kopua has up her sleeve, the Casey Cut-off is perhaps the most impressive.
It works like this: when the opposition feeder is positioned circle edge, rather than sit back on the shooter, Kopua will try to cut the ball off at the source. She rushes at the ball carrier, timing her jump for when the ball leaves the feeder's hands and bats it away like a volleyball block, sometimes, if the ball is floated, she can intercept it outright.
Very few defenders have the anticipation, timing, elevation and sheer audacity to pull this off. Kopua is the master of it.
She has attempted this hundreds of times in her career - the last time was October 11 last year.
It was supposed to be a special night for the inspirational captain. While her team were in the midst of a disastrous Constellation Cup series against Australia, there would at least be some small reason to celebrate the third test in Sydney with Kopua to become the Ferns' most-capped skipper.
She brought up the milestone, but her night ended abruptly, painfully, and oh so heart-breakingly, five minutes into the final quarter. After leaping into the air to swat away the ball as she has done so many times before, Kopua's patella tendon gave out on landing. With no longer anything tethering her patella to her shinbone, she screamed in shock and agony when she looked down to find her kneecap jutting out of her thigh.
Kopua still can't bring herself to watch netball. She went along to a Magic training match last week but lasted only until halftime before that sick feeling at the pit of her stomach got too much.
"I don't mind the conditioning side of things that we're doing with the girls and I try to participate in everything that I can. But actually watching a game, I just ... I don't know," she shudders. "It's probably because I'm so far away from being able to do that myself, I guess."
For now Kopua prefers to focus on what she can do rather than what she can't.
Much like the same slow and cautious approach she takes to climbing stairs at the moment, Kopua's rehabilitation has been broken down into microsteps. In her first physiotherapy session, the challenge was to bend her knee to a 40-degree angle. Each week she was able to bend it a little further, until finally she worked her way up to a full 90 degrees.
They might seem like small milestones, but to Kopua they are massive. Her husband Terry and her family are just as committed to her rehabilitation as she is, with each new hurdle she clears cause for major celebration.
"When I hit those small little targets I get quite emotional - like just being able to put on my own sock for the first time was huge."
The next step was getting her active. After starting out at just 10 minutes on the bike, she is now up to 70 minutes of continuous cycling, and on Thursday Kopua slowly but defiantly made her way to the top of Mt Maunganui.
There is a year-planner on the bedroom wall of her Hamilton home that maps out the road ahead to get her to the World Cup in August.
It will likely be April before she can attempt to run again, let alone perform the sharp changes of direction and explosive leaps that make her one of the best intercept-takers in the game.
That all but rules her out of returning to court for the Magic in this year's ANZ Championship.
But the brilliant defender is determined she will be there for what is likely to be her last tilt at a world title.
The timeframe is tight.
A player who typically takes a few games to warm into the season, Kopua will need to be back on court for the Ferns' July internationals against England to give the New Zealand coaching staff any level of comfort about taking their prize defender away to the Sydney tournament.
"If I'm not right then I'm not right, but I'm going to do everything possible to be right," said Kopua.
"Some days I wake up and think 'oh God, am I going to be able to make it?' and other days I think there's nothing that will stop me."
