Mhlongo suffered an ACL tear during Pirates’ 1-0 Absa Premiership defeat to SuperSport United on August 11, for which he required surgery.
The 24-year-old was initially expected to be out for up to 10 weeks, but he is recovering ahead of schedule.
“Brighton has started training with the team. However, he is only allowed to partake in straight line movement for this week,” Bucs physiotherapist John Williams told the club's website.
Meanwhile, fellow Buccaneers keeper Samora Motloung has resumed full training after shaking off a knee problem.
Felipe Ovono, who stood in the 1-1 draw with Mpumalanga Black Aces last Friday, and Siyabonga Mpontshane have played in Mhlongo's absence.