Vidal, 27, had knee surgery in May, but still played a huge part for Chile at the World Cup.
Louis van Gaal's concerns over the problem are reportedly all that is standing between Vidal and a move to Premier League giants Manchester United.
Allegri, whose team are in Australia to face an A-League All Stars team on Sunday, confirmed Vidal was back running.
"He is running since yesterday, but we will evaluate day by day his condition and when it is best for him to start playing again," Allegri told a news conference in Sydney on Friday.
Sunday's clash at ANZ Stadium will mark the first, and probably last, time Juventus great Alessandro Del Piero takes on his former club.
Juve goalkeeper and captain Gianluigi Buffon said it would be "beautiful" to face his former club and Italy team-mate, but hopes he can keep the attacker off the scoresheet.
Former Sydney FC star Del Piero, who is without a club, will captain the All Stars.
"Of course having a game against Alex is something completely new for me and for Juventus of course," Buffon said.
"It will be a beautiful experience to have this game against Del Piero and I hope there will be chances for everybody to entertain the public.
"Hopefully one of these chances won't be Alex scoring a goal against Juventus."
