Bayern visit the Imtech Arena on Saturday to face a Hamburg side that has endured a week of turmoil after coach Mirko Slomka was sacked on Tuesday.
Slomka was immediately replaced by Hamburg's Under-23 coach Josef Zinnbauer, who is tasked with reviving a team that has taken just one point from their first three league games.
And Guardiola, whose players are coming off a dramatic 1-0 UEFA Champions League win over Manchester City on Wednesday, is wary of a backlash from their hosts.
"Hamburg is always one of the most important clubs in Germany and has a very aggressive team," he said.
"I expect a tough game. I remember when his [Zinnbauer] predecessor Slomka came to Hamburg, they had the first game against [Borussia] Dortmund and won 3-0."
With Bayern having been in action just three days earlier, Guardiola remains unsure how many of his first-choice players will face Hamburg, although the injured Bastian Schweinsteiger, Franck Ribery, Thiago Alcantara, Javi Martinez and Holger Badstuber will not travel with the team.
Guardiola added: "I'll speak with my players, especially those who played on Wednesday. Afterwards, we decide."
However, one player that is unlikely to feature is defender Mehdi Benatia, for whom the match with City represented his first since July.
There is better news surrounding winger Arjen Robben, though, with Guardiola hopeful that the Dutchman will be ready despite struggling with knee problems prior to Wednesday's clash.
"For Benatia it is probably too much to play a game every three days," Guardiola said. "Before the match against City he had not played in over two and a half months.
"Arjen trained well yesterday [Thursday]. I hope he is ready for the next games."
