By ESPNSTAR.com staff
Marin moved to Stamford Bridge at the start of the season but has struggled to force himself into manager Roberto Di Matteo's first-team plans, playing just 20 minutes in the Capital One Cup so far.
His lack of game time has already seen him linked with a return to the Bundesliga, and more specifically Gladbach, where he began his career at before moving to Werder Bremen in 2009.
Nonetheless, when asked if he was considering a move for Marin, Favre refused to give a definitive answer and was cryptic in his reply.
"I don't want to comment on this," he told Bild. "We'll see in winter [when the transfer window opens]."
Gladbach stunned onlookers last term as they finished fourth in the league and qualified for the preliminary round of the UEFA Champions League, but they have been disappointing this season and are currently 8th on the table.
A key factor in their poor performances this year has been the absence of last season's top scorer Marco Reus, who moved to Borussia Dortmund in the summer, although Marin appears to be a perfect replacement for his fellow Germany international.