The Steelers are concerned that defensive end Stephon Tuitt tore his biceps Sunday against the Browns, ESPN's Adam Schefter reports.
According to Schefter, Tuitt will have an MRI Monday, and if his biceps is torn, he will be done for the season.
On Saturday, Tuitt signed a five-year, $61 million extension with Pittsburgh.
Tuitt, 24, is in his fourth season. He was a second-round pick in 2014 out of Notre Dame.