All Whites coach Danny Hay is confident that captain Winston Reid will make the cut for the Costa Rica showdown, in what would be a massive boost for the team.
Reid has been under an injury cloud, after a slight groin strain picked up towardsthe end of training on Wednesday night.
That meant he sat out the 1-1 draw with Oman – where the plan had him starting – and didn't train with the team on Friday.
But Hay expects Reid to be lining up in Wednesday morning's match.
"He had got a bit cold," said Hay. "He felt some tightness in his groin, which is why he immediately stopped. But today he said he felt good so I don't think we have any major issues."
Reid took part in Sunday's training, looking relatively untroubled in the warmup runs and passing drills. His presence is vital for New Zealand, as the leader of the backline and the most accomplished defender.
Reid sets the defensive tone, and his ability to read the play and be exactly where he needs to be is critical. The All Whites would still have faith in any replacement, but the players gain huge confidence from Reid's presence on the field.
Intensity is building for the team. While there were still smiles and laughs at training, there was an undoubted sense that business time is here.
The team trained at Abdullah bin Khalifa stadium, another spectacular World Cup training venue and home of the local club Al Duhail.
It was noticeable that the goalkeepers spent an extended period dealing with crosses and high balls, a precursor to what is expected to come their way on Wednesday.
Hay said there were no other injury concerns in the camp, with no issues arising out of the Oman game.
The team had their final intense session on Sunday, before they begin to taper down.
Monday's training will be shorter and sharper, while the session 24 hours before the match will consist of walk-throughs, tactical shape and set pieces.
Hay said that while was the intensity and focus was building, it was also important to keep the players as relaxed as possible. For many of them it will be the biggest match of their lives and burning up any extra nervous energy will only detract from their performance.
"It's exciting, it's such a big opportunity for us," said defender Niko Kirwan. "It's a big opportunity for us to show our value and show what we are worth. It's a massive match but also really exciting and we need to go out and give it our all and take it to them."
Kirwan added that the disparity in the world rankings (Costa Rica are at 31, 70 places higher than the All Whites) wouldn't necessarily be reflected on the field.
"Football is a sport that anything can happen – look at Italy and North Macedonia," said Kirwan. "But in saying that, we are confident in how we have been training and the style of play we have. It is going to be a really good match and a great test for us."