City make the trip to the Allianz Arena with both teams already through to the last 16 of the competition.
Demichelis moved to Bayern from his native Argentina in 2003 before leaving the Germans for Malaga in 2011 having won a wealth of trophies.
"I played here for seven-and-a-half years and experienced a lot," he told reporters. "Tomorrow is a very emotional day for me, in my career and in my life.
"We have to play with real fire in our stomachs. It's a great team we're playing and this is great preparation for us."
Demichelis joined City from Atletico Madrid in the summer on a two-year deal.