Jacobson might have thought he would get his chance at a start in last week's opening loss to France when captain Sam Cane was forced to pull out of the game with a back injury that will also keep him out of the Namibia match.
Coach Ian Foster instead elected to bring Tupou Vaa'i, who normally plays lock, off the bench to play blindside and switched Dalton Papali'i to the openside flank in place of Cane.
Jacobson did get a decent run off the bench as New Zealand chased the game in the second half but was relishing the chance to be on the pitch from the start this week.
"This week has been focusing on myself mainly," he told a news conference in Toulouse.
"I'm pretty excited about it - getting a crack in the six jersey. I've just been getting excited about what I can bring to the field."
Foster earlier this week called up loose forward Ethan Blackdadder as a replacement for winger Emoni Narawa and with first-choice blindside Shannon Frizell on the mend, Friday could be Jacobson's only chance to stake a claim to a starting role.
Like all of the New Zealand forwards, Jacobson will be desperate to stay on the right side of the referee after the All Blacks were heavily penalised against France.
"There was probably a few areas that have been cleaned up on, particularly around the breakdown and a little bit around discipline - there were far too many penalties," he said.
"It makes it pretty tough to play rugby when you concede that many penalties."
The loss to France was New Zealand's first in a World Cup pool match but the narrative from the All Blacks camp this week has been that ultimately it will not have a major impact on their bid for a fourth world title.
"Losing's not ideal," he said. "(But) we know that we need to be winning to win this competition regardless, so I don't think a whole lot changes from now."
