London - Manchester City's problems at the heart of their defence got even worse on Tuesday with the news John Stones is set to miss up to six weeks with a muscular injury.
The Premier League champions now have just one fit senior central defender available in Nicolas Otamendi with Aymeric Laporte ruled out until at least the end of the year after knee surgery.
"Injured this morning in training. Four, five or six weeks. It is a muscular problem," Guardiola said ahead of City's Champions League opener away to Shakhtar Donetsk on Wednesday.
Stones is expected to miss Premier League clashes with Watford, Everton, Wolves and Crystal Palace, as well as Dinamo Zagreb's visit to the Etihad in the Champions League in two weeks' time.
City are already counting the cost of not buying a replacement for departed captain Vincent Kompany, who left to become player-manager at Anderlecht at the end of last season.
Guardiola hinted that holding midfielder Fernandinho will be moved back to deputise in defence, whilst youngsters Eric Garcia and Taylor Harwood-Bellis may be given the chance to impress in the coming weeks.
"As a manager, it is an incredible challenge with just one central defender, Nico," added Guardiola.
"But I believe a lot with something people don't know about; the spirit and the commitment for everybody to make a step forward with a big commitment to solve this problem.
"I think Fernandinho, and Garcia and Harwood-Bellis from the academy will come forward for the next month."