Thomson got two bites at his debut in the 21-11 win against Ireland in torrential rain at Westpac Stadium on Saturday night.
The flanker entered the game just 90 seconds into the second half as a five-minute blood-bin replacement for Rodney So'oialo, then got to play the last six minutes as the All Blacks held on for a dull but efficient victory.
Thomson hardly touched the ball and was penalised for bringing a maul down, but nothing on the field could dampen his excitement at becoming the 1073rd man in black.
"During the week it was great being part of the camp, but I didn't really feel like an All Black," Thomson said.
"I think it sunk in when I got my jersey today.
''It's a pretty surreal moment holding a test jersey in your hand.
''To go into the changing room and pull the black jersey on, to do the haka, to get pumped up - that's when I felt I was an All Black."
Thomson was presented with his first All Black jersey by manager Darren Shand.
He took it back to his room, laid it on his bed and stared at it for a long time.
He thought about how far he had come, from junior days in Ashburton and schooling in Christchurch to the Otago University club and eventually the Highlanders.
No way was he giving up that first jersey.
Thomson had a spare to exchange for an Irish top, and said he was already planning where his framed first All Black jersey would be displayed.
Thomson became the university club's 44th All Black and received messages of support from members through the week.
Shortly before his test debut, he heard University A had regained the Cavanagh Trophy from Southern.
