All Blacks captain Kieran Read is in doubt for the Rugby Championship Test against Argentina after missing training in Buenos Aires with an illness.

The No.8 failed to travel with the team to their training venue on Thursday, two days out from the Test at La Plata.

The 27-year-old remained at the team hotel and All Blacks management said an update on his condition will be made on Friday.

New Zealand coach Steve Hansen would have difficulty covering for the 55-Test veteran if Read is ruled out.

Just five loose forwards are in tour squad, including regular captain Richie McCaw, who is recovering from a knee injury which ruled him out of selection for this Test.

Read’s spot at the back of the scrum would probably go to Liam Messam, who would shift from the blindside flank.

Steven Luatua, who is named in the reserves, would then come onto the side of the scrum but Hansen would be left without loose forward backup on his bench.

Hooker Dane Coles and prop Ben Franks are the only extra forwards on tour who weren’t named on Thursday in Hansen’s 23-man squad for the Test.

A new captain would also need to be found, with none of the 14 other players in the starting 15 having led their country.

Read is the only player to play every minute of New Zealand’s seven Tests this year. The other is centre Conrad Smith.