"I wouldn't see any other reason unless anyone tells me otherwise," Linehan said.
NFL Network insider Jason La Canfora cited a source with knowledge of the situation in reporting that the Lions don't plan to shut down Best indefinitely at this point and are handling his concussion according to normal league protocol.
Later Thursday, Best's agent, Tony Fleming, shot down a CBSSports.com report that claimed people close to the running back were encouraging him to sit out the remainder of the season.
"There is no truth that he was recommended to sit out the rest of the season," Fleming said, according to ESPN.com. "Obviously we're being cautious because it's not his first (concussion), but we do expect him to be back as soon as he is cleared which will probably be a week-to-week evaluation."
Still, no one exactly knows exactly when Best can play. The running back hasn't said much and offered the following on Twitter: "Thanks for all your tweets and prayers. I'm taking everything one day at a time."
Best hasn't practiced this week after suffering what he said is the third concussion of his football career. He had one in the Lions' second preseason game this year and another in 2009, his final season at California when a spectacular fall sent him to the hospital with a concussion and sore back.
With no timetable for Best's return, the Lions are looking for backfield help. Their Tuesday trade to acquire former Pro Bowl running back Ronnie Brown from the Philadelphia Eagles in exchange for Jerome Harrison was voided Wednesday because a brain tumor was discovered during Harrison's physical, a source told NFL.com senior writer Steve Wyche. The Oakland Press reported that the Lions were trying out running backs Thursday.
"All our backs are a little bit different, all of them bring a little something different to the offense," Schwartz said. "We'll use anybody that we have available on Sunday to the best of their abilities."
The Associated Press contributed to this report.