Rieko Ioane and Jerome Kaino could both miss this week's test against France.
Kaino, who made his return after over three months out the team at No 8, injured his posterior cruciate ligament in the All Blacks' 31-22 win over the Barbarians at Twickenham.
Liam Squire is expected to return at blindside against the French in Paris, but if Kaino's knock is significant enough, his involvement in the remainder of the tour will be in serious doubt and he could be forced to return home. That would be a tough setback for the 81-test veteran attempting to re-establish his place in the competitive pecking order while Vaea Fifita also continues to make his case heard.
Ioane's situation does, comparatively, not seem so severe though he, too, could miss the French test after struggling with the mumps.
Ioane did not train last week in London or attend the scratchy win over the Baabaas - instead staying in isolation at the team hotel.
Mumps is a contagious viral infection, and the All Blacks have been wary of other squad members catching it. Recovery time usually ranges from anywhere between two to three weeks.
This is the second mumps case to hit this squad. Rookie centre Jack Goodhue missed the opening match against the Baabaas with the same illness, staying at home to recover, before rejoining the team in London last Friday.
"It's unrelated to Jack Goodhue because they haven't been in contact," All Blacks coach Steve Hansen said as the team ventured from London to Paris on the train. "It's obviously come out of Auckland somewhere. It will be touch and go. He trained this morning it will depend on how well he comes through the week we'll wait and see."
Hansen downplayed fears the virus may infect others.
"Doc has done a great job he isolated him so no we're not worried."
Losing Ioane would be a blow. The 20-year-old has been a star on the left wing for the All Blacks, scoring nine tries in 10 appearances since moving past Julian Savea.
Ioane's form has been so compelling that he is considered a strong favourite for World Rugby breakthrough player of the year.
Seta Tamanivalu, who made his first start in the No 11 jersey against the Baabaas and performed well there, would be favoured to retain that role if Ioane is ruled out.