Thomson, who has never worn the No 7 jersey for Otago or the Highlanders, replaces skipper Richie McCaw for the team to take on Samoa in a test at New Plymouth tomorrow night.
McCaw is not available for the match because of injured ribs he suffered in the win over the Springboks in Durban on August 16.
For Thomson (26), it will be a chance to show his wares in a wide-ranging role, which should suit his speed and athletic ability.
Hopefully, it will be a clear night in New Plymouth, and with the All Blacks wanting to have a meaningful hit-out before their Tri-Nations series decider against Australia in Brisbane on September 13, it could be a night for Thomson to remember.
All Blacks coach Graham Henry and selectors Wayne Smith and Steve Hansen had previously started Wellington loose forward Rodney So'oialo at openside flanker earlier this year, when McCaw was injured.
He started two tests against South Africa before the selectors decided to go for Auckland openside flanker Daniel Braid in the loss against Australia, as the game was expected to be quicker.
But the selectors have decided on Thomson for tomorrow night, to see how he shapes up with the No 7 on his back.
Thomson has all the attributes of a good openside flanker: he is quick across the ground, good at the breakdown, and does not miss many tackles.
Otago coach Steve Martin said Thomson had played at openside flanker for University A a few years ago, and had been outstanding, and was excellent in the breakdown area.
Martin said the All Blacks selectors had given no indication to Otago management it was thinking of using Thomson at openside flanker so he wore the No 6 jersey for Otago in its loss to Hawkes Bay last Friday night.
Thomson had a relatively low-key match against Hawkes Bay as an aggressive defence by the visitors shut down many of Otago's options.
Thomson becomes the sixth player to wear the All Blacks No 7 jersey since McCaw made his All Blacks debut against Ireland in November 2001.
So'oialo will start the test in his preferred position at No 8, with Jerome Kaino completing the loose forward trio.
So'oialo will also captain the side in his 50th test.
The selection of the side shows how far the All Blacks have come since last year's fixation with rotation, naming a near first-choice line-up.
A powerful backline will run out while the forward pack has a solid look about it, and the Samoans may be in full damage control.
Henry said it was important to play another game before the match against Australia, and was pleased to have the opportunity to play Samoa in Taranaki.
Samoa has been handicapped by many of its European-based players being unavailable.
Along with the unavailability of McCaw, winger Sitiveni Sivivatu is out with an injured ankle, lock Brad Thorn has a sore hamstring, while prop John Afoa injured his shoulder in Auckland's loss to Waikato and will not play.
Canterbury's Ben Franks has joined the squad to provide additional cover at prop.
Four backs are named on the reserve bench, and with no obvious replacement should a lock get injured, Kaino or Sione Lauaki may be pressed into service.
Test teams
To play in New Plymouth
All Blacks: Mils Muliaina, Richard Kahui, Conrad Smith, Ma'a Nonu, Anthony Tuitavake, Dan Carter, Jimmy Cowan, Rodney So'oialo (captain), Adam Thomson, Jerome Kaino, Ali Williams, Anthony Boric, Greg Somerville, Andrew Hore, Tony Woodcock.
Reserves: Keven Mealamu, Neemia Tialata, Sione Lauaki, Piri Weepu, Stephen Donald, Isaia Toeava, Rudi Wulf.
Samoa: Alatasi Tupou, Reupena Levasa, Pale Toelupe, Jerry Meafou, Esera Lauina, Uale Mai, Notise Tauafao, George Stowers, Alafoti Faosiliva, Semo Sititi, Chad Slade, Filipo Levi (captain), Heroshi Tea, Loleni Tafunai, Simon Lemalu.
Reserves: Lafoga Aoelua, Roysiu Tolufale, Maselino Paulino, Simaika Mikaele, Junior Poluleuligaga, Roger Warren, Romi Ropati.
