"He's trained really well and got through it and I think we said last week we had a progression plan for a number of the guys who brought niggles into the week and overall came through pretty good.
"In fact, everyone was training at nearly 100 per cent in the last training session.
"It's just disappointing that a mischievous person has tweeted something with no information behind it."
Williams had battled off a host of injuries to make New Zealand's World Cup squad in the first place.
Knee surgery had threatened the 34-year-old's World Cup place, and that after dealing with wrist, knee and shoulder injuries in the previous season.
Asked whether New Zealand were considering any call-ups, Foster added: "I've just answered that question. There's no people needed."
This article first appeared on RugbyPass.com and is republished with permission
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- Rugbypass