Initial X-rays revealed that Onwenu fractured his right ankle during Sunday's 20-3 win over the Steelers, Mike Reiss of ESPN.com reports.
The Patriots will likely confirm the injury in the coming days, but Onwenu will almost assuredly miss time and could be headed to injured reserve. Greg Van Roten is the most likely candidate to start at right guard Week 3 against the Jaguars after he came on to replace Onwenu following his departure Sunday.