Nathan Aké has said Manchester City will “massively” miss Kyle Walker if he leaves in the winter window after the 34-year-old informed the club he wishes to do so.

After City’s Saturday’s 8-0 FA Cup third-round rout of Salford City, Pep Guardiola revealed the defender was left out of the match-day squad after his request on Thursday to “explore the option” to play abroad. Milan are interested in signing Walker, though a move to Saudi Arabia is not thought to be an option currently.

Related: Kyle Walker asks to leave Manchester City in search of a move abroad

Aké was asked if Walker’s leadership would be a loss. “Massively. He’s a big player for us, a big character,” the Dutchman said. “He is a good guy as well, I’m very good [friends] with him. Let’s see what happens. There’s no doubt he’s been a massive player for us.”

Since joining from Tottenham in July 2017 for £45m, Walker has won six Premier League titles, the Champions League, two FA Cups, four League Cups, the Uefa Super Cup and the Club World Cup.

“He’s massive for us over the years,” Aké said. “This year as well, a big character in the squad. He deserves a lot of praise for all the years he’s been a top player for this club.”

City’s victory over Salford included a goal from the 19-year-old Nico O’Reilly, who played as a left-sided defender, plus a hat-trick from the attacking midfielder James McAtee, who is 22. Divin Mubama, a 20-year-old forward signed from West Ham in August, also scored. Rico Lewis, 20, an unused substitute, has recently become the first-choice right-back ahead of Walker. Aké pointed to these players as an indication that Guardiola is bedding in the next generation at City.

“We’ve got a good mix of young players,” he said. “You see [against Salford] there’s many young players. We’ve got older ones, too so at the moment there’s a good mix and the club has always been good at finding the right balance between ages. I’m sure they’ll continue to do that.”