Thought was given to playing Luke Ronchi as a specialist batsman, replacing Jimmy Neesham. Now it's a case of a spin all-rounder to replace a medium pace all-rounder.
"We played a [practice] game here in Sharjah, saw the wicket we're likely to play on and, with Dan being over here, the possibility of playing three spinners is one we couldn't give up," Hesson said. "We haven't named our side but his experience and knowledge in these conditions, combined with the fact he's fit and strong again will help."
Vettori bowled nine overs in the New Zealand A one-day match against the United Arab Emirates on Sunday, taking one wicket for 41 runs.
In September, Vettori said he was ready to resume limited overs bowling after a sustained rehabilitation on a damaged Achilles tendon, but doubted he could continue to meet the requirements of tests.
"I can't guarantee the amount of overs [required] to play a test match and don't want to get in way of Ish [Sodhi] and Mark [Craig] in their development. The World Cup's the goal. Tests would put too much of a strain on the body at this stage of my career."
The difference with this scenario is that the usual demands for a spinner bowling away against Pakistan are likely to be less if the workload is shared three ways.
The long run Other examples of New Zealand test longevity
*Bert Sutcliffe 18 years 72 days
*Daniel Vettori 17y 295d [if he plays on Wednesday]
*Sir Richard Hadlee 17y 158d
*John R Reid 15y 356d
*Merv Wallace 15y 265d
*John Wright 15y 35d
*Andrew Alderson travelled to the UAE courtesy of Emirates