The All Whites could take the field on Thursday with a radically reshaped defensive unit.
Winston Reid's withdrawal not only robbed the team of their best player and captain, it also created a significant headache for the New Zealand brains trust.
The central back three was set in stone - Tommy Smith marking on the left, Reid on the right and Andrew Durante mopping up just behind. Now tinkering is needed.
Ben Sigmund could yet come in as a straight swap for Reid, but yesterday's training suggested another solution is in the offing.
For most of the session Ivan Vicelich was playing in the sweeper-type role with Durante as a marker alongside Smith. Jeremy Christie, who hasn't had a club for most of the past two years, took Vicelich's usual spot in central midfield alongside Michael McGlinchey.
Playing Christie would appear to be a major gamble, but Herbert has been impressed with his output since he came back into the fold in the past few months and the 30-year-old could perform a close marking role in midfield.
Whether Herbert goes for Sigmund or Vicelich at the back, the All Whites will struggle to contain Mexico.
Reid was the quickest NZ defender and neither of the two replacement options is blessed with pace.
The other conundrum comes up front, in what Herbert admits may be his toughest decision.
It's the one where the All Whites have genuine options and at this stage Chris Wood, Jeremy Brockie and Kosta Barbarouses are believed to have the inside running.
However, it would be hard to leave Marco Rojas out, given his obvious talent, while Shane Smeltz has been at the centre of many of the big moments in recent years. Rory Fallon's aerial prowess and presence is also a wildcard.