The 19-year-old Brazilian has been introduced from the bench in two of Chelsea's three Premier League fixtures, including Sunday's 2-1 loss to Arsenal. Estevao came close to rescuing a point at Stamford Bridge when his late effort forced a save from David Raya.
His reduced role comes after he made 12 Premier League starts last season, scoring eight times across all competitions under Enzo Maresca and Liam Rosenior.
"Este is ready, he's training well. [Against Arsenal] he had a very good impact, he has a great chance. So he's fully involved and with a very good attitude every day," Alonso said via the Evening Standard.
"100% [he has an important role], because of his potential, because he's so young, but he's in that process to adapt and to learn quickly. And the season is going to be long."
Chelsea now turn their attention to the Carabao Cup, with Leeds visiting Stamford Bridge in the third round on Wednesday. Alonso's side will be looking to respond to their first competitive setback under the manager.
Levi Colwill is back in contention after overcoming a fitness problem, having remained among the substitutes against Arsenal. However, Moisés Caicedo, Marco Palestra, Emmanuel Emegha and Jordan Henderson are still sidelined.
Michael Carrick has challenged Manchester United to make the most of their return to the Champions League and believes his squad is capable of competing with Europe's top sides.
Chelsea secured their place in the fourth round of the EFL Cup with a thrilling 6-3 victory over Leeds United at Stamford Bridge on Wednesday night.
Martin Odegaard struck in the second half to give Arsenal a 1-0 Champions League victory over Napoli in Naples, maintaining the Gunners' perfect start to the 2026-27 season.
Liverpool head into their Champions League opener against Atletico Madrid with manager Andoni Iraola facing an early test of his squad management.
