Milan have done little to improve their squad since winning their first Serie A title for the first time in 11 years last season, with Belgian attacking midfielder Charles De Ketelaere (21) their only major signing of the summer.
However, their 4-2 win against Udinese in their 2022/23 campaign opener last week came with a couple of pleasant surprises after Ante Rebic (28) and Brahim Diaz (23) made a rare appearance on the scoresheet.
"We need to be an interchangeable team... We are strong, we need to all feel important here, but no one is essential," Pioli told reporters ahead of Sunday's match at Atalanta.
"What is essential is mentality and work."
When asked if Milan were in pole position in the race for the title, Pioli said the campaign was very balanced as there were seven or eight strong teams.
"We need to continue on our path, focus on the next game and work on becoming more and more competitive," he said.
"It will be a campaign so balanced that it will be difficult to earn as many points as in the last season.
"Everyone will face some difficulties, even with the teams they don't expect to do so. The ones who are the most consistent in delivering both results and performance will win."
Pioli expects an intense match on Sunday which would see two sides who know each other well and who both take the initiative and have an offensive playing style.
"They (Atalanta) have changed a couple of players but not their frame. They bring together organisation with intensity and quality," he said.
