The Black Cats thumped West Ham 3-0 on the opening day of the season.
“We are getting better. The players are growing with different experiences,” Le Bris said.
“At the same time, you can’t be comfortable in the Premier League.
“It’s important to say that earning points in this league is tough, especially for a newly-promoted side. It’s very difficult to win points.”
Le Bris also stated: “West Ham are a good, experienced team and they are struggling, which shows how difficult this league is,.
“They have won their last two games and probably deserved more against Forest. They have recruited two new forwards and we will have to stop them. It is another exciting challenge.
“It’s a game of key moments. Even if we do things well, they have players who can hurt us, like Jarrod Bowen.”