Prater has been struggling with illness recently and missed the Broncos' final practice in Denver before they travelled to New Jersey for their last week of preparation.
However, Fox has revealed that he had been treated by the team's medical personnel and is in no doubt that the kicker would be ready by this weekend.
"He feels much better, our [doctors] take good care of him, got plenty of fluid in him, he's got the right meds. Again, it's a virus, everybody gets it and he'll be fine come next Sunday," Fox told reporters.
Prater made 25 of his 26 field goals in the regular season, including an NFL record 64-yarder, while he has also made five of his six kicks in the playoffs so far.