Dutchman Robben was injured in a Euro 2016 qualifier against Iceland last month and has yet to train with the team but Guardiola refused to rule him out of the game against visitors Dortmund, who are in second place, four points off Bayern.
"He has not trained with us. Of course I need to see him but he is in the last phase of his (recovery) process," The Spaniard told reporters on Friday. "But I do not know if he can play on Sunday."
Bayern have been in sparkling form even without wingers Robben and Franck Ribery, who has not played since March, with new signings Douglas Costa and Kingsley Coman shooting out of the blocks.
The Bavarians, eyeing a record fourth straight Bundesliga title, have won all seven of their league games so far and also crushed Dinamo Zagreb 5-0 on Tuesday to top their Champions League group.
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Dortmund, also undefeated, kicked off their campaign with five victories but have stumbled to two consecutive draws in their last two Bundesliga matches.
While football fans across the country and some 200 more nations will be watching Germany's top two teams battle it out for domestic supremacy, Guardiola did not want to place too much importance on this one game.
"It is still only October and only three points are available," he said. "Nothing has been decided. This is no final, it is about three points. After the match nothing will have been decided."
(Reporting by Karolos Grohmann, editing by Pritha Sarkar)
