Massimiliano Allegri called for Juventus to become more "unpleasant" as he said the Bianconeri must remain in Scudetto contention by the time Serie A breaks for the World Cup in November.
Juventus have made a solid if unspectacular start to the new campaign, taking nine points from their first five Serie A matches while remaining unbeaten.
But Allegri's men have faced criticism for their tepid style, and were outplayed by Paris Saint-Germain when they suffered a 2-1 defeat in their Champions League opener on Tuesday.
That result means the Bianconeri have started a Champions League campaign with a loss for just the second time in their 23 participations in the competition (W13 D8), also losing to Barcelona in September 2017 (3-0).
Allegri believes Juventus were too "nice" on their trip to France and called for them to toughen up ahead of Sunday's match against Salernitana.
"After 2-0 there was a good match, a good reaction. I don't like that Juve played well after the 2-0, and we have also become nice," Allegri said on Saturday.
"That's not good. I am very angry, you have to be unpleasant, so we are successful. Otherwise we get used to being nice and pretty and losers, and that's not good!
"You have to take the positives from the game. The boys know it, we have a game to face with the right seriousness.
"We work day-by-day to create conditions to achieve goals. But it takes something else. You don't have to be nice or pretty."
Juventus have been beset by injuries – including those suffered by new arrivals Paul Pogba and Angel Di Maria – in the season's early weeks, and are also waiting on the recovery of Federico Chiesa, who has not featured since undergoing surgery on the anterior cruciate ligament in his left knee in January.
With Serie A set to pause for almost two months from early November, Allegri believes remaining in contention until the World Cup starts will be crucial for their Scudetto hopes.
"At this moment, with the numerical difficulties, we need to arrive in November in the best possible ranking condition," Allegri said.
"I know that there is a great desire to work, to return to winning even if it is not easy. We were missing players from the beginning, important players.
"In January we will recover everyone but we cannot ruin everything this month.
"[What] if we take away the equivalent of Pogba, Di Maria and Chiesa from the other teams?
"We must be happy with what we are doing, knowing that the prospects are rosy."
On Chiesa, Allegri added: "I hope to have him before the World Cup break. He will be at 100 per cent in January, now there is a month left, he is working on the field alone.
"We hope to have him as soon as possible with the team in a partial role."
Juventus are looking to defend a strong record against Salernitana when they host Davide Nicola's men on Sunday; the Bianconeri have won four of the teams' previous six Serie A meetings (D1 L1), keeping five clean sheets.