"We don't have a definite timetable but we feel the best way for him to recover properly is maybe to get out of the busyness of here and to be at home."
Blues midfielder George Moala has come in as back-up to Ryan Crotty, Malakai Fekitoa and Seta Tamanivalu, but he is under an injury cloud himself and, according to Foster, won't be running at 100 per cent until tomorrow.
The team's other injury concerns ahead of the first test against Wales at Eden Park a week on Saturday are lock Sam Whitelock, still on light duties due to a hamstring strain, and halfback Tawera Kerr-Barlow, who is recovering from a hand injury.
Kerr-Barlow, not with the squad for the past two days due to a family issue, will probably start passing work at the end of the week, Foster said.
"The players are in recovery mode, the coaches are in full-steam mode, so it's a matter of trying to get a nice balance," Foster said after the team trained at Trusts Stadium in Waitakere yesterday.
"We haven't been able to do too much too fast on the training ground but there's plenty of content for us to chug our way through this week."
Meanwhile, the Chiefs have announced Ngatai has re-committed to them for the next two seasons.
"The opportunity to play for the Gallagher Chiefs and All Blacks was a massive driver for me in signing for a further two years," Ngatai said.NZME.