Mason replaced Jose Mourinho after his sacking this week and has the chance of winning a Cup winner's medal in only his second game in charge.
"My mind, my focus is fully on the match. Maybe once the season is done and I can rest and get some time to think, then I can look back and be very proud.
"This isn't about me or my ego in going up against Pep. This is Tottenham versus Manchester City. We'll be doing all we can to get the better of them. They'll be doing the same. It's one of those one-off games. Anything can happen. We'll go there believing, with confidence, and hopefully it can go our way on Sunday."