De Bruyne, 34, decided to join the Serie A champions after his contract at Man City expired at the end of last season.
The veteran attacking midfielder has impressed during pre-season, notably scoring a brace in Napoli’s 3-2 friendly win over Girona.
Speaking at a press conference on Wednesday ahead of the friendly against Olympiacos, Conte couldn’t help but praise his impact.
The Italian said: "He's fully immersed himself in this environment, he's perfectly understood the importance of the work, never a word out of place, he was a very welcome addition for the players who were already here.
“He's had a top career and came here to get back into the game, without missing a second of training. He's always done everything, available, now we're trying to find the right balance with the four or the three (midfielders).
“There will be a lot of matches, an exceptional lad, he's surprised everyone."
Conte was then asked about Lukaku, to which he responded: "He can do even more, because he's a key player in winning the Scudetto, because we bought him for €30 million and the cost/return ratio was top-notch.
“Training after so many years of not doing so can bring him a lot of benefits. He's in the midst of his development, he's one of the team's key players, and we need players who can also acquire some leadership.
“From Romelu to Giovanni Di Lorenzo, (Stanislav) Lobotka, (Frank) Anguissa, and, quietly, (Amir) Rrahmani. I need the old group, I need them to take on even more responsibility, because so many new players are coming in, and we need people who can always lead the way even in difficult situations. For Romelu, may he have an even better season than last year. That's my hope."