The 44-year-old departed Camp Nou after four silverware-laden years in charge in 2012 and faces the Catalans for the first time since leaving in the first leg of their Champions League semi-final.
"It is a very emotional game for him," said Low. "He has played for Barcelona and of course been their coach and had great success.
"Whether he will benefit from knowing Barcelona inside out on Wednesday, I don't know. At the top level you know most things about the best clubs, there aren't too many surprises."
Guardiola has had to contend with a lengthy injury list which sees Arjen Robben and Franck Ribery both absent through injury, as well as David Alaba, Holger Badstuber and Sebastian Rode.
That said, Low still believes Bayern have enough quality to trouble Barca and is anticipating a tight affair over two legs.
"Of course Bayern have a chance against Barcelona. Barcelona are probably in the best form at the moment but Bayern, despite their injuries, still have a lot of quality.
"For me it is a duel at eye level and I look forward to seeing two fantastic teams in action."