Quarterback Mac Jones was sacked five times and landed on the bench after throwing an interception in the red zone late in the fourth quarter of the Frankfurt game, the NFL's 50th regular-season game outside the United States.

Back-up quarterback Bailey Zappe sealed New England's fate with another interception on the final drive.

The loss saw the Patriots off to a 2-8 start for the first time since Belichick took the helm in 2000 and the coach of famously few words had even fewer to explain the horrific run by the six-time Super Bowl champions.

"Obviously a disappointing game - similar theme that we've had other games this year: just too many missed opportunities," Belichick told reporters.

"Just got to play better situational football and do a better job taking advantage of the opportunities we have."

Belichick has been on the NFL sidelines for nearly half a century. But this annus horribilis has prompted speculation of a once unthinkable split between the 71-year-old and the team he propelled to greatness with now-retired quarterback Tom Brady.

Retired linebacker and current ESPN analyst Tedy Bruschi, who picked up three Super Bowl rings under Belichick during his career, urged owner Robert Kraft to let his former coach see things out.

"When people (are) talking about 'Should Bill Belichick be fired mid-season?' - listen, we are not the Las Vegas Raiders," Bruschi said, referring to Belichick's former protege Josh McDaniels, who was fired as head coach of Las Vegas days ago.

"You let Bill finish this out, Mr Kraft."

Belichick and the team will have an extended period to regroup as the Patriots are on a bye week before facing the New York Giants on the road.

"As a team, we're just not doing enough things that we need to do to win," he said.