A back injury scare for wicketkeeper Brendon McCullum on Friday left New Zealand with potential headaches over the balance of their first cricket test team to face Australia next week.

On a forgettable day for the tourists at the Sydney Cricket Ground, McCullum sat out the final session with back spasms, a vomiting Jesse Ryder was quarantined in the team hotel and the fielders dropped five catches against New South Wales.

The blunders cost a combined 131 runs and helped the hosts claim a 43-run first innings lead on the second day of the four-day tour match, ending 309 for six in reply to New Zealand’s 266.

Pacemen Chris Martin and Iain O’Brien were the pick of the bowlers with two wickets apiece, but there wasn’t enough sustained pressure as NSW added 126 in the final session.

While New Zealand manager Lindsay Crocker said Ryder’s condition was improving after nearly two days unable to keep food down with a “mystery bug”, McCullum was potentially of more concern.

McCullum remained in the pavilion as New Zealand returned for the final session, Aaron Redmond took the gloves and Mark Gillespie took the field, which reduced the tourists to 11 fit players.

Coach John Bracewell even donned the whites late in the day, just in case of another mishap.

Vice-captain and key batsman at No 5 McCullum had complained of back spasms and sought immediate attention on the physiotherapists’ table.

If the soreness continued and McCullum played in Brisbane as a batsman only, Gareth Hopkins would take the gloves as he did at late notice in the third test against England in Nottingham in June.

In the absence of allrounder Jacob Oram (back), it meant Hopkins or captain Daniel Vettori would have to move into the top-six if they wanted to play five specialist bowlers.

Crocker insisted McCullum, who kept wicket in three ODIs and two tests in Bangladesh, wasn’t yet in doubt to wear the gloves in Brisbane.

“We expect Brendon should be right in the morning and that’s the way we’re planning for it,” Crocker said.

“Gareth’s due over here before the start of the test match just to cover for the eventuality of something happening last-minute with Brendon.”

Crocker said despite McCullum’s continued back problems, there was still no thought of him relinquishing the gloves for good.

“He does experience a bit of tightness in the back, it’s the nature of his job.

“There’s really no talk of that at this stage. It’s been a discussion topic for other people but it really hasn’t been a serious consideration in this team.”

Ryder meanwhile was able to stomach liquids for the first time late today and was hoped to be back on solid food and potentially return to the field later in the four-day match.

He was quarantined from his teammates yesterday after suffering a suspected virus, and placed on an intravenous drip.

“He saw the doctor today and he was satisfied he’s on the right side of it. He’s taking liquids in a normal form and he’s getting his hydration back which is the first stage of recovery.”

It was a day of hard toil for the New Zealand bowlers on a flat SCG pitch, not helped by the fielding effort.

McCullum and Ross Taylor each held two catches but also dropped a sharp chance apiece, while Redmond, Daniel Flynn and Tim Southee were the other culprits.

NSW captain Dominic Thornely led the way with 85 while 19-year-old opener Philip Hughes hit a brisk 64 after being dropped on 35.

Allrounder Moises Enriques had a life on 21 and went on to 55 before captain Daniel Vettori claimed him as his only wicket.

Vettori ended with one for 66 off 25 overs.