He's been advised he has a small cartilage tear on the same knee he had cleaned out a few years ago and might need surgery when he returns to New Zealand.
The Warriors will be interested observers, especially considering five-eighth Thomas Leuluai has already been invalided out of the tour and it could take time to repair his injured groin. Both could have interrupted pre-seasons.
It's been a frustrating time for Vatuvei over the past couple of seasons as he constantly battles with injury but he's trying to stay optimistic.
"I have been struggling a few times but I just have to fight through it and believe in myself that I can keep going and look after my body,'' he said.
"I worry about [what I might be like after my career] - that's the downfall - but if I look after myself now it might pay off in the long run. I just have to keep in a routine.''
It's one that presently doesn't amount to much on-field training throughout the week and he's thankful of the additional training he did in the last off-season when he lost 8kg training to take on Olympic gold medallist Eric Murray in a charity boxing match.
"That has really helped me out, a lot,'' he said. "Right now I'm trying to maintain that and I'm doing a lot of extras [outside of regular team training]. It's even harder with the eating, you tend to gain a bit weight.''
Vatuvei had hoped to be playing Tonga in the quarter-finals ("even though I don't play for them, I represent them no matter what,'' he said) but is looking forward to catching up with Scotland hooker Ian Henderson on Saturday morning. Literally, catching up.
"If I get the opportunity to play, that's my first port of call,'' he laughed. "I will be running straight at him.''
Kiwis coach Stephen Kearney will settle on his playing 17 closer to kickoff but has left out Josh Hoffman, who is struggling with a shoulder strain but who also hasn't nailed down the fullbacks position, in favour of Kevin Locke.
"I think Kevin is the best man for the job this week,'' said Kearney.
Frank-Paul Nu'uausala looks to have won the interchange position over Alex Glenn and Greg Eastwood but Kearney still needs to make a decision around which front-rower will drop out of his four prop rotation.
Kiwis squad to play Scotland at Headingley, Leeds, on Saturday (9am NZT): Jesse Bromwich, Kieran Foran, Bryson Goodwin, Shaun Johnson, Sam Kasiano, Kevin Locke, Issac Luke, Simon Mannering, Ben Matulino, Sam Moa, Jason Nightingale, Frank-Paul Nu'uausala, Frank Pritchard, Elijah Taylor, Roger Tuivasa-Sheck, Manu Vatuvei, Jared Waerea-Hargreaves, Dean Whare, Sonny Bill Williams (two to be omitted).