Holcomb (illness) has been downgraded and ruled out ahead of Sunday's matchup against the Colts, Burt Lauten of the Steelers' official site reports.
The 29-year-old from North Carolina was unable to practice both Thursday and Friday due to an illness, so it's no surprise that he won't suit up Sunday. While Holcomb misses his first game of the season in Week 9, expect Malik Harrison to play an expanded role in Pittsburgh's inside linebacker corps.