Midfielder Sonny Bill Williams may miss the rest of the All Blacks' season-ending northern tour after injuring his shoulder in New Zealand's nailbiting 16-15 win over England at a sold-out Twickenham.
Williams lasted just 30 minutes before he was forced from the field with a shoulder injury, and replaced at second five-eighth by Ryan Crotty.
All Blacks coach Steve Hansen said the 33-year-old Williams had sustained a grade one AC joint shoulder injury, and could be out for up to two weeks.
The All Blacks play Six Nations champions Ireland, who beat Argentina 28-17 overnight, in Dublin next week before meeting Italy in Rome on November 25.
Hansen said it was unclear whether Williams would be replaced.
"We haven't had time to discuss that - we'll see how he pulls up tomorrow morning, and have a chat about it later."
The All Blacks recovered from 15-0 down to beat England 16-15, their 15th win in 16 matches between the two in their first clash for four years.
In difficult, rainy conditions England raced into a big lead after a fantastic opening, kicking at every opportunity and forcing the All Blacks into errors and scoring tries through wing Chris Ashton after two minutes and hooker Dylan Hartley midway through the first half after an unstoppable rolling maul.
The world champions hit back just before half-time with a try by impressive fullback Damian McKenzie and a Beauden Barrett penalty.
In the second half Barrett's first test drop goal and another penalty hauled the All Blacks into a 16-15 lead which they held with five minutes remaining.
England thought they had won it with a try to openside Sam Underhill only for the TMO to rule that team-mate Courtney Lawes had been offside before charging down the clearance kick that sent the flanker through.
England had a couple of other chances to set up the drop goal or score but the All Blacks defence held strong to claim the narrowest of victories.
Coach Eddie Jones said England, who face Japan next week, will take real heart from their performance.
"It was a really good step forward because you benchmark yourself against New Zealand," he said.
"I thought we played the final 20 exceptionally well, we'll take enormous confidence from that. We're excited about where we're going."
With half-time beckoning a rare Owen Farrell error, when he sent the restart straight into touch, allowed New Zealand to make ground and close the gap to 15-10 at the break with a Barrett penalty.
"England were very, very good and we showed a lot of character in a hostile environment after being 15-0 down and in the weather conditions," Hansen said.
He also thought the TMO call was straightforward.
"There's no doubt he was offside, just about in the halfback's back pocket," he said.
"What was going through my mind was were they brave enough to make the right decision - and they were."
The All Blacks now move on to Dublin and their clash with Six Nations champions Ireland, before ending their northern tour against Italy in Rome on November 25.