New Zealand's famed fitness enabled them to put together a sound display ahead of further pool games against Georgia and the United States.
Gillies Kaka and Tim Mikkelson took knocks but are expected to remain fit.
"It was good to see guys like Peter Ahki using their step," Tietjens said.
"We started well and put pressure on. I was pretty nervous going into the game because the heat was a telling factor."
Compounding Tietjens' nerves was New Zealand's quarter-final exit at the last World Cup in Dubai four years ago. He sounds tense.
Of the other key World Cup contenders: Fiji looked ominous beating Tonga 45-0, defending champions Wales defeated Uruguay 33-5 and England dismantled Portugal 21-7.
The New Zealand women's side start their campaign tomorrow in the opening match against Tunisia (5pm NZ time).
They have an arduous day playing further pool matches against the Netherlands and Canada.
New Zealand 31 (K.Baker, P.Ahki, S.Stowers 2, G.Kaka tries, Kaka 3 con)
Canada 12 (H.Jones, N.Dala tries, N.Hiriyama con)
* Andrew Alderson travelled to Moscow courtesy of New Zealand Rugby.