"EJ did look improved today," Marrone said.
Marrone said that he would review Thursday's practice to see how Manuel performed but did not give a timetable on when he would name a starter.
"The earlier I can make a decision I think the better it is for the team," he said. "That’s how I approached it all year. This way the team knows what we have going into it."
Meanwhile, Marrone said that he is "close" to ruling out safety Aaron Williams (ribs), who missed last Sunday's game and has yet to practice this week.
Marrone also said that he hasn't had recent contact with receiver Stevie Johnson, who remains in California following the death of his mother.
Here is the Bills' full Thursday injury report:
DID NOT PARTICIPATE
S Aaron Williams (ribs)
WR Stevie Johnson (personal)
RB Fred Jackson (ribs)
QB EJ Manuel (knee)
WR Marquise Goodwin (knee)
QB Thad Lewis (left shoulder)
DT Kyle Williams (Achilles)