Collins was released by Manchester City at the end of last season, and has been training with the Stags since they returned for pre-season earlier this month, Shirtliff told the Nottingham Evening Post "He's done all right in the pre-season he's been involved in so far, settled in well and quietly gone about his business,"
"But he's not been here anywhere near long enough for me to make a decision yet and I want to see what he is like in games.
"I'll take a look at him in the friendlies that we have arranged and then decide if we want him after that."