Stacey Jones praised Tonga's performance against Samoa last week, calling the Pacific rivals' encounter a compelling spectacle.
The Kiwis coach expects another step up when New Zealand meets Tonga in Saturday's Rugby League World Cup semi-final.
"The game goes to another level now, and no disrespect to the other teams, but we're playing a really good team."
Jones said Tonga are strong across the field and will pose a formidable challenge, requiring New Zealand to improve on its recent performances.
New Zealand has made progress during the tournament, despite an opening game that did not meet the team's expectations.
Jones said the Kiwis responded with good play in Christchurch, then delivered a strong performance last week.
He said he was "Just happy with where we're at."