Dundee United skipper Mark Reynolds feels like he is going into the unknown when facing former club Aberdeen in the Scottish Cup.
Reynolds spent seven seasons at Pittodrie but will come up against a team under fresh management in Sunday's quarter-final.
"The thing for me is it will be an unknown," the 33-year-old said.
"Any time I have faced Aberdeen before it's a manager I know very well, who I worked under for about seven years, so you knew how they would set up, what the ethos of the club was, how he wanted them to play football, even down to the way they do set-pieces. That will all change.
"So for me it is the unknown but we are very lucky that at Dundee United we have a very good backroom staff, good video guys who will get us as prepared as they can.
"But their limitation is they are only working with a manager who has had two games and not a lot of time on the training ground to bed in.
"So an Aberdeen team that is an unknown and they are all trying to show a new manager they deserve a place in the starting XI.
"But we have been on a good run and managed to get results when we need them so we will go into the game confident we can get a result."
Glass is looking to kick-start his Aberdeen career but United are also under relatively new management following their return to the top flight.
Micky Mellon is looking to emulate Ivan Golac and Peter Houston in winning the Scottish Cup in his first season in charge at Tannadice and Reynolds knows from experience what that could do for the future.
The former Motherwell and Sheffield Wednesday defender won the League Cup under McInnes in 2014 during the manager's first full campaign.
"Dundee United have won trophies in their history, so it's a team that should be challenging and at least giving itself a chance of silverware," Reynolds said.
"We have come up this year and probably done a lot better than people maybe give us credit for. We have stayed in the league comfortably, were a point outside top six, and we have a chance to go to Hampden.
"We have to try and take that. When Derek McInnes went in at Aberdeen, that's what set the tone and there is no reason why we can't do that as well."