The Baltimore Sun reported Friday that Reed "had a really good week" of practice according to coach John Harbaugh.
However, Reed told The Sun that he wasn't sure about his status for Buffalo.
"We'll see how it feels [Saturday]," Reed told The Sun.
When Reed is ready to return, the Ravens plan to open a roster spot for the All-Pro safety by placing offensive tackle Jared Gaither on injured reserve, a source told ESPN NFL Insider Adam Schefter.
Gaither injured his back during the offseason. The former Maryland product admitted early in training camp that he overdid it by drastically reducing his weight to 311 pounds after playing last season at roughly 340 pounds.
Reed's backup, Tom Zbikowski, has played well in a starting role, but The Sun reported he is doubtful against the Bills.
"The chances of him going are slim at best," Harbaugh told The Sun. "I wouldn't count on Zibby."
Reed was placed the PUP list in September after undergoing offseason hip surgery.
Information from The Associated Press contributed to this report.