Judy Murray says there is no timetable for son Andy's return to competitive action following his hip injury.
But she says he will definitely be fit enough for his exhibition match against Roger Federer in Glasgow in November.
"He's going to be fine by then," she told BBC Scotland.
"He hasn't put a timescale on it and I think that's the sensible thing to do because you never know how your body is going to respond, so it's always safer not to put a timescale on it."
Murray, who has not played since Wimbledon, pulled out of the US Open two days before the August tournament.
Following his inaction, the 30-year-old has dropped to number three in the world behind new number one Rafael Nadal and number two Federer.
"He's carrying on his rehabilitation at the moment doing everything he can to get back into shape," added his mother.
While Murray is likely to play Federer in Glasgow, Judy hinted that being competitive in the Australian Open at the start of next year will be a big ask.
"It's quite a different thing playing exhibition matches to playing on the tour where you have to win five matches to win a tournament," she added.