Richardson was limited Sunday after he was injured in the first quarter, but the Browns overcame the loss of their top offensive player with a 34-24 win over Cincinnati to snap an 11-game losing streak that stretched back to last November.
Richardson's injury is considered painful. He got hurt when he took a helmet to his side and had an MRI on Monday. The Browns likely will limit his participation in practice this week to give him as much rest as possible.
Richardson finished with just 37 yards on 14 carries and spent most of the second half on the sideline. But Richardson's backup, Montario Hardesty, picked up the slack and rushed for 56 yards and scored his first touchdown in the NFL as the Browns (1-5) also snapped a 12-game losing streak inside the AFC North.
Richardson had said Sunday he believed he would be able to play in Week 7 against the Colts.
"I took a shot, but I'll be back," Richardson said. "I'll be ready for next week."
The Browns had formulated their game plan to feature Richardson, who had rushed for 109 yards and scored two touchdowns against the Bengals (3-3) when the teams played last month in Cincinnati. But after Richardson got thumped in the first quarter, the Browns turned to Hardesty, who had barely gotten on the field in Cleveland's first five games this season and has been slowed by injuries for several years.
Hardesty came through with Richardson cheering on his teammate. Hardesty hit the holes when they were there and created space when it didn't appear there was any room to run.
"You've got to love it," Richardson said Sunday. "Montario, he is a beast. A lot of people think Montario is one of those guys that is not going to try to run you over or not going to be in there for the thick and thin, but Montario is one of those guys who is going to give everything he can on each and every play."
Information from AFC North blogger Jamison Hensley and The Associated Press was used in this report.