Current San Francisco 49ers left tackle Joe Staley answered the question. It turned out to be Anderson's teammate in Cincinnati of seven years — defensive lineman Justin Smith.
Staley and Smith went against each other once during their careers — the Niner tackle's rookie season in 2007 when San Francisco hosted the Bengals at Candlestick Park. After that, Staley went against Smith regularly, but it was on the practice field as a teammate. The 49ers signed Smith the following offseason, and the two remained teammates for seven years until Smith announced his retirement on May 18, 2015.
"The Cowboy" accumulated 87 sacks to go with his 880 combined tackles and 17 forced fumbles over his 14 NFL seasons.
H/t to Chris Biderman of the Sacramento Bee for the find.