Robben has been sidelined with back and groin injuries which forced him to pull out of the Holland squad for their Euro 2012 qualifying fixtures with San Marino and Finland but Heynckes is hoping he will be back soon to help the club both domestically and in continental competition.
Bayern are top of the Bundesliga after four games and host Freiburg on Saturday, then travel to Spain to face Villarreal next Wednesday in the first round of Champions League matches and host Manchester City on September 27.
Heynckes said: "Every player at Bayern is important, because we're a very ambitious club. Take Thomas Muller for example, who turned in a world-class performance for Germany against Austria. But a fully-fit Arjen is capable of settling a game by himself.
"Naturally, we need him, especially in the difficult Champions League fixtures.
"He's in much better physical shape now. He spent 30 minutes on the treadmill yesterday, and the pain has almost completely gone away.
"We'll have to wait and see what happens with the pelvic inflammation which is causing the problem."