The 26-year-old endured a difficult tail end to the 2018-19 season, with knee and ankle injuries severely stunting his presence in the Hoops' line-up.
But it appears the Socceroos midfielder could soon make his way back onto the pitch for the first time since May's Scottish Cup final win over Hearts.
"He is in rehab," Lennon told the Daily Record. "Obviously from the knee injury last season and he picked up an ankle knock in the Cup final.
"He’s back out now, he looks great, really looking in good condition so hopefully he won’t be too far away but he’s missed the whole of pre-season so he has a bit of work to do."
Celtic played a total of 63 competitive matches last season and look set for another fixture-filled calendar, having already kicked off their UEFA Europa League qualifying campaign with a 5-2 aggregate victory over FK Sarajevo.
