Hernandez, who did not make the trip to London, missed three games with the injury earlier this season.
ESPN.com senior NFL writer John Clayton reported that Hernandez suffered a setback in practice earlier this week. ESPN NFL Insider Adam Schefter added that the ankle has not responded to treatment and that Hernandez is struggling to make cuts.
The Patriots have a bye week after Sunday's game, which gives the injury extra time to heal.
Hernandez was injured early in the Sept. 16 loss to the Cardinals when teammate Julian Edelman was tackled and rolled up on the tight end's right ankle. Hernandez missed the next three games. He returned Oct. 14 for the Patriots' game with the Seattle Seahawks, making six catches for 30 yards and a touchdown, and had five catches for 54 yards against the Jets last week.
Hernandez, who signed a lucrative five-year contract extension before the start of the regular season, has 17 catches for 143 yards and two touchdowns this season. He set career bests with 79 catches, 910 yards and seven scores a season ago.
In addition to Hernandez, the Patriots have officially ruled out six other players for Week 8, including both of their starting safeties, Patrick Chung (shoulder) and Steve Gregory (hip). It's the second consecutive week that the duo will be sidelined together (and the fourth straight game missed for Gregory), and likely will lead to rookie Tavon Wilson and Devin McCourty (normally one of the team's starting cornerbacks) filling in as their replacements, as they did in Week 7.
Cornerback Ras-I Dowling (thigh) was placed on injured reserve, ending his season.
The Patriots are required to list just seven inactive players on game day, but have also declared 11 others as questionable for the contest, including linebackers Jerod Mayo and Dont'a Hightower, tight end Rob Gronkowski and wide receiver Wes Welker.
Information from ESPN senior NFL writer John Clayton and ESPN NFL Insider Adam Schefter was used in this report.