Pep Guardiola conceded Manchester City will have to play the Community Shield with an inexperienced side as much of his senior squad rests following the rigours of last season and Euro 2020.
City started their pre-season preparations with a 2-0 win over Preston North End on Tuesday.
Guardiola fielded Joao Cancelo, Nathan Ake, Ruben Dias and Benjamin Mendy in defence in front of young American goalkeeper Zack Steffen, while Fernandinho and Riyad Mahrez were the only other fully fledged first-team players to feature.
City reclaimed the Premier League title from Liverpool last season while also winning the EFL Cup and reaching the final of the Champions League, where they lost to Chelsea, in a tightly packed campaign that followed swiftly on from the end of the delayed 2019-20 season.
With much of his team then featuring in the European Championship, Guardiola has found himself bereft of options as he plots a defence of the league title and another assault on the one prize that continues to elude City.
They will now welcome Barnsley to their Academy Stadium on Saturday in the last warm-up before the Community Shield against Leicester City at Wembley on August 7.
Speaking to the club's official website after the win over Preston, Guardiola said: "We have to adapt with just three or four players from the first team, every week is coming players, hopefully they come back and they can train.
"I know we don't have time because in 10, 11, 12 days we have the Community Shield with just three players but we're going to play with the players [from the] second team and we're going to try.
"Every season is so tough so the mending is important, we need rest, mentally.
"The managers and the backroom staff we have time but the players were in the European cup, they didn't have time, that's why they have to rest three or four weeks."