Borussia Dortmund defender Neven Subotic has left the door open for an eventual return to the United States, the country he left as a 17-year-old.
Subotic returns to Dortmund following a loan spell at Cologne last season.
The former Serbia international, under contract until 2018, had found playing time limited under old boss Thomas Tuchel and has vowed to fight for his place under new coach Peter Bosz.
"There is a new situation for me at BVB this summer," he told kicker. "There is a new coach I need to get to know, and vice-versa.
"I don't know how big a chance I will get under him. I need to get a feeling for which type of player he prefers. I want to leave a good impression from day one."
Subotic said he would not "make a move out of financial reasons," adding: "Of course, from a personal point of view the United States would be tempting.
"My family lives there, and it would be nice to see them more often. But I need a sporting challenge -- that's the main point."
Despite Matthias Ginter leaving for Borussia Monchengladbach, Subotic faces strong competition in central defence from Marc Bartra, Sokratis Papastathopoulos, Sven Bender and new signings Omer Toprak and Dan-Axel Zagadou.
But he said that competition would not faze him, adding: "I have been at BVB for many years, and I've won titles with the club.
"It would not be interesting if there were no competition. I never shy away from challenges."