Maddison has been out of action since suffering ankle ligament damage in a 4-1 loss to London rivals Chelsea in the Premier League on November 6th.
England international Maddison impressed after joining Spurs from Leicester in a £40 million move in June, scoring three goals in 12 appearances.
Maddison is now set to feature against City but Postecoglou has still to decide on his starting line-up.
"He's trained all week and he is fine," Postecoglou told a pre-match press conference on Thursday.
"He is available and ready to start... when someone is available, I assume they are ready to start.
"Whether they do or not depends on what I see with everyone else tomorrow and I usually make those decisions on game day.
"Like I said, the beauty of it is he's got through the week really well and is ready to go."
