The Citizens trained on Monday morning and a 19-man squad has since travelled to Slovakia ahead of their first away match in the newly-expanded Champions League.
However, the 2023 champions will have to cope without star playmaker De Bruyne, who remains sidelined with a groin injury picked up in City's opening Champions League match against Inter Milan (0-0) a fortnight ago.
De Bruyne has since missed Man City's last three domestic matches against Arsenal, Watford and Newcastle United in which Guardiola's side have drawn twice in the Premier League either side of their EFL Cup win over the Hornets.
Prior to the 1-1 draw with Newcastle last weekend, Guardiola suggested that De Bruyne could return to the first-team fold either before or after the international break.
The Catalan coach has since issued a fresh update on De Bruyne's condition, confirming when he hopes the Belgian will make his comeback.
When will Man City's De Bruyne return from injury?
Speaking at a press conference in Slovakia on Tuesday evening, Guardiola said: "Hopefully after the international break [Kevin] will be back.
"Everybody (else) is ready - we will put out the best team possible to compete and beat [Slovan Bratislava]."
Man City's small 19-man squad is also missing midfield lynchpin Rodri, who has been ruled out for the rest of the season with an ACL injury and underwent successful surgery last Friday.
The Citizens are also still having to cope without Oscar Bobb (leg fracture) and Nathan Ake (muscle), although the latter could be ready to return after the international break along with De Bruyne.
If De Bruyne is indeed not ready to return until after the international break towards the end of October, that would rule him out of Saturday's Premier League clash with Fulham at the Etihad Stadium.
De Bruyne will presumably not be fit to represent Belgium in UEFA Nations League matches against Italy and France and could potentially target a return for Man City on October 20 when they travel to Molineux to face Wolverhampton Wanderers in the Premier League.
Phil Foden to step up in De Bruyne's absence?
In the absence of De Bruyne, last season's PFA Player of the Year Phil Foden could be tasked with operating in an advanced midfield role against Slovan Bratislava.
Foden has endured a disrupted start to the new season, but Guardiola has backed the England international to return to his best in the coming weeks.
"I have some doubts about many things but I know Phil will be back. He feels good," said Guardiola. "Playing at St James' Park (for 25 minutes as a substitute) I felt something that I like and I didn't see for example against Watford.
"You cannot forget for a month and a half, two months he did not train, with niggles and problems with his health. Now he is smiling and finding his rhythm, we cannot forget he was the best player in the PL last season.
"I have no doubt his love of football, his passion like he has since the first time he land in the first team for Man City."
Teenage starlet Rico Lewis, naturally a right-back, is also a contender to operate in midfield on Tuesday, as he did from the start against Newcastle last weekend.
Man City's 19-man squad vs. Slovan Bratislava:
Kyle Walker, Ruben Dias, John Stones, Mateo Kovacic, Erling Haaland, Jack Grealish, Jeremy Doku, Stefan Ortega, Ilkay Gundogan, Bernardo Silva, Josko Gvardiol, Manuel Akanji, Savinho, Matheus Nunes, Ederson, Scott Carson, Phil Foden, Rico Lewis, James McAtee