But he is not putting any victory drinks on yet.
When Jerome Kaino made the decision to head to Japan at the start of the season, there were plenty of candidates in the queue to wear the No 6 jersey for the All Blacks.
Messam was one of those in the picture and, thanks to performances over the past month, appears to have leapt clear of the field.
He said the rivalry involving him, Victor Vito and Adam Thomson was keeping him highly motivated.
"Competition brings the best out of me, there is no doubt about that. You make sure you have an edge to everything. You cannot relax at all. When it comes to Saturday, that is the fun part, really," he said.
Training was intense, he said.
No-one wanted to give anyone a break.
Messam, though, keeps to the party line about supporting team-mates. He was keen to help out Vito when the Wellington man started at blindside flank last week.
"I'm one of those guys who like to help out my team-mates. Last week, it was very terrible conditions but I thought Victor played really well.
"I was trying to give them some advice on what I could see from the bench at halftime."
Being on the bench was better than not being in the squad at all.
"You are more frustrated at home watching footy but in a team environment you just want to support the boys the best way you can."
Messam knows tomorrow night's game will be all about being tough and strong against a committed opponent. But that can not always be on his shoulders.
"I do not think it just comes down to the No 6 jersey. I think it comes from one to eight, especially against South Africa. You have to get physical dominance against them."
Some have raised doubts about Messam since he first made the All Blacks in 2008.
But he has matured in the past year, and he credits getting things right off the field.
"I have sort of learned from other people not to think about rugby 24/7 and that, I think, has really helped. I think things just clicked in me."
He said his son, Jai (2), brought him back to earth and helped get his mind off rugby all the time.
