The battle between Ngatai and Malakai Fekitoa is shaping as a key factor in a crucial game from which the winner take second spot in the New Zealand conference.
Ngatai will again be paired in midfield with Anton Lienert-Brown, after Sonny Bill Williams' return from a back injury was delayed another week.
The loss of Cruden and the irregular appearance of Williams has hardly helped Ngatai's job in the middle of the park. But, previously injury-prone himself, the 24-year-old New Zealand Maori captain has this season transformed into a backline leader.
"Charlie's a pretty intelligent football player," said assistant coach Tom Coventry. "He's a big part of our attack group and he speaks good sense when it comes to attack options and strategies. He's pretty influential in our backline."
That influence arrived only after he found physical fitness. After an outstanding ITM Cup campaign with champions Taranaki, Ngatai has overcome an early injury setback to turn in his best Super Rugby campaign.
"It comes down to having less injuries this season and it's working well for me," Ngatai said. "I had an awesome campaign with the 'Naki and I've tried to bring that confidence through to Super Rugby this year."
That confidence is clear in Ngatai's decision-making and distribution, facets that have been near flawless this season. When matched with a speed and skillset that has produced five tries, it's no surprise Ngatai is on the All Blacks' radar.
"That's something I'm trying to push for by playing consistently," he said.
"Just being named in the All Blacks squad would be a massive achievement for myself, and getting that first cap would be unreal, a phenomenal experience."