Gross-Matos (hamstring) was activated off the 49ers' injured reserve list Monday, Adam Schefter of ESPN reports.
The Penn State product has not played since San Francisco's Week 5 win over the Rams due to a hamstring injury, but it now appears he's nearing a return. Despite being activated off IR, Gross-Matos is still listed as questionable for Monday night's matchup against the Colts. If active for the Week 16 contest, he'll likely operate as one of the 49ers' top reserve defensive ends.