The Steelers' linebacker will miss four weeks after undergoing surgery to remove loose cartilage from his knee, although coach Bill Cowher does expect him to play in the opener Sept. 11 against Tennessee.
Porter injured the knee Tuesday while celebrating his one-on-one victory over free agent rookie tackle Ulish Booker.
Porter became upset when teammates chided him for losing a first pass-rush match-up with Booker, and so Porter called for a second encounter. After beating Booker, Porter stomped on the chalk mark which designates an imaginary quarterback, and hyperextended his knee.
The knee became swollen that night and Porter underwent an MRI examination Wednesday morning. The surgery was performed by team surgeon Dr. James Bradley.
"Joey had problems with the same knee a couple years ago," said Cowher. "I think we'll have him back a little bit sooner than Duce."
Duce Staley underwent knee surgery Monday and is also expected to miss four weeks.
Cowher said James Harrison will replace Porter, 28, at right outside linebacker. Harrison, 27, started two games last season.