Taylor and Franklin, both battling hamstring strains, batted in the Seddon Park nets ahead of tomorrow's third Chappell-Hadlee Trophy one-day international against Australia but were still rated doubtful.
"Ross and James both trained but we're going to leave it until the last minute to make a decision. We're hoping they both can get through but I'd say they're both probably 50-50 at this stage," Vettori said.
"Probably if Ross could get through (he would play), but James because he needs to bowl as well, we'd be a bit more cautious with him. If Ross was able to get on the park we'd be pretty grateful for that." Key batsman Taylor would be left to pass himself fit to play, and the decision won't be made until tomorrow.
Vettori said if both were ruled out, Scott Styris would probably bat No 5 with new cap Shanan Stewart at No 6 after he was called into the side as cover yesterday.
Vettori (neck) and Brendon McCullum (back) were both fit to play but Gareth Hopkins would keep wicket again.
With Stewart's inclusion and the injury concerns, New Zealand's squad swelled to 15 players yesterday.
With the series poised 1-1 after Australia's 12-run win in Auckland, tomorrow was a series-defining match.
"It's probably the most important game of the series. The team that can go 2-1 up only needs one more to win the series so we're trying to put everything into this game," Vettori said.
"We enjoy playing here, it's a great cricket ground and the guys are pretty excited about being here."
