The 18 year-old has been a revelation for Saints in the first six weeks of the Premier League.
Fraser told the Daily Echo: "We tell Tyler not to change anything. We tell him to go into games with no fear and do what you want to do.
"Don't go into a game with the mindset that you need to change. Get what you need out of the game.
"If you run your socks off for 60 minutes and you get the best out of yourself, someone else will come on and finish your job for you.
"If he's going to have that mentality, he's going to be a top, top player. Mateus looks superb technically as well.
"They are good people. You can get these players who come in and are technically good but not that good for the squad. Both of them work hard.
"The boys will help them and work hard for them. Tyler will do his thing and then someone behind him will do his work for him. You will see the best of them."