Glenn Phillips has been summoned as last-minute batting cover after illness hit the New Zealand camp ahead of the final Test in Sydney, forcing Kane Williamson and Henry Nicholls to sit out training for the second day running.

Mitchell Santner, whose position in the side was under scrutiny after two poor outings, has also come down with the bug, leaving the possibility that New Zealand's resources will be stretched very thin as they aim to avoid a whitewash. Jeet Raval, who was dropped after the Perth Test, is currently the one spare batsman in the squad and the decision has been taken to fly in the uncapped Phillips on the eve of the game.

Phillips averages 42.54 from 23 first-class matches - with four hundreds - and struck a century for New Zealand A against England late last year.

"We've obviously got a few balls up in the air at the moment and we want to be on the safe side and have options," New Zealand coach Gary Stead said. "Glenn has been in terrific form this season and has good versatility with where he can bat and the roles he can play.

"He's been around the T20 team for the past couple of years so should feel comfortable in the environment. We're still hopeful Henry and Kane will pull through and we will give them every chance to prove their fitness. If one or both are ruled out then we will consider our options and most importantly how they balance the side for this final Test."

Should Williamson be unavailable - and it would take a very severe illness to sideline him - Tom Latham would be the likely replacement as captain, although last year, when Williamson was ruled out of the Christchurch Test against Bangladesh that was subsequently cancelled following the terror attack , Tim Southee was in line to lead the side.

Latham took on the official duties at a reception with the Australian Prime Minister Scott Morrison on Wednesday and also did the pre-match press conference.

"[Kane] is obviously a great leader amongst this group and he's passionate about this group, so I'm sure if there's any chance of him playing, even if it is a small chance, he'll certainly be playing," Latham said. "It's gone around the team a little bit which obviously isn't ideal but fingers crossed, they're resting up today and hopefully they'll wake up and be good to go.

"If we lost those guys it would be disappointing but we've got a squad of 15 who are passionate about this team, and whatever side we do play has the backing of the whole group that it's the right team for the job.

England's preparations for the first Test against South Africa last week were severely impacted by illness which swept through the majority of the squad in the first few weeks of the tour and continued to strike players while the Test was in progress.

It leaves New Zealand's planning up in the air although if everyone is available for selection there is the potential for two changes to the bowling attack with Matt Henry replacing the injured Trent Boult and Will Somerville coming in for Santner. While the surface is expected to turn, it is thought unlikely they will field two spinners, particularly after the workloads Southee and Neil Wagner have had during the first two Tests.

The series has been a chastening experience for New Zealand after they arrived with the hope of competing with Australia having risen to No. 2 in the Test rankings. They failed to cross 200 in the first three innings before Tom Blundell's defiant century in Melbourne, in his first Test as an opener, provided belated resistance.

"We haven't played our best brand of cricket and I know the guys are excited about getting out there over the next five days and trying to put a good performance on the board," Latham said. "Yes, the series is lost but it's the Test Championship and points are up for grabs. We'll be doing our best to put a good performance out there."

Tim Paine was expecting Williamson to be standing with him for the toss and was focused on Australia not letting up in their intensity after a dominant Test season which has seen them win all four matches, including two against Pakistan, so far by huge margins. In the Ashes series last year, Australia produced a poor performance at The Oval after they had retained the urn with a match to spare but Paine was confident his team had learned from the experience.

"I wouldn't say we took our foot off the pedal [at The Oval], but we've certainly learned how to handle that experience of having the emotional high of the win then switching back on really quickly," he said. "We spoke this morning about making sure that we turn up tomorrow with the same energy and focus that we turned up at the Gabba. All I've asked tomorrow is we turn up expecting New Zealand to come out hard and expecting it to be another fight for five days. We feel if we can match them in that area that eventually we'll be able to wear them down."

GMT 0800 The story was updated to include the news of Phillips' call-up.

Andrew McGlashan is a deputy editor at ESPNcricinfo