Mane made his Premier League debut in defeat at Liverpool last weekend.
On his Anfield appearance, the 18 year-old told the club's website: “It felt good getting my first start in the Premier League. I feel like I deserved it with my hard work in training and when I’ve come on the pitch every game.
"I just kept working with my head down, I kept working and working, then the new manager came in and trusted me, and now I'm getting what deserved – game time.
“I found out the day before in a meeting that I was starting. I was buzzing. I told my family, then felt confident. At first there were a lot of nerves, but then after a bit you realise this is where you want to play, where you want to be.”
On facing United, Mane also said: “We need to start the game how we ended the game, and if we concede don’t let that get to us. Keep our head up, keep going, fight and try to get goals.
“It’s changed a lot under Rob. Everything's changed around the building. He pushes us every day to get the best out of us. We just need to get a win.”