FOXBOROUGH , Mass. — The warden of the AFC East beat the carnival barker of the NFL. Bill Belichick over Rex Ryan. Again. And the beat goes on.

Another Patriots victory — a gritty 20-13 decision over the Bills on Monday night at Gillette Stadium — kept their undefeated season intact at 10-0 and it humbled the bombastic Ryan, who had spent the lead-up to the game showcasing his colorful personality, chatting away about Belichick, quarterback Tom Brady and the nemesis Patriots.

Another New England win over an AFC East opponent, another win over the Bills (the Patriots are 27-3 against Buffalo since 2001), another New England division title on the precipice of being clinched (the Patriots can sew up the AFC East next week with a win over Denver and a Jets loss to Miami).

And another Belichick win over Ryan, the ninth in the coaches’ past 10 meetings and 11th in 15 career meetings.

“We’ll take it, and move on to Denver,’’ Belichick said matter-of-factly after the game.

“Of course they want to bury me,” Ryan said of the Patriots before the game. “No question they want to beat me.’’

And so they did, leaving the somber Ryan’s tone after the game barely above a whisper, lamenting again about not being good enough to beat the Patriots, who prey on opponents like Ryan’s that make just enough mistakes to lose.

“We knew we were a better football team,’’ Ryan said, referring to his group that lost a 40-32 decision to New England in a Week 2 game that was not as close as the final score indicated. “But we’re not good enough. Like always, we came up short, despite being here and having them on the ropes. But they made plays. That’s what championship teams do. We’re not there yet.’’

The Bills looked as if they might take control of the game on a lucky break early in the third quarter, when an “inadvertent whistle’’ was blown by line judge Gary Arthur while a Brady pass to Danny Amendola looked as if it would go for a 69-yard TD and a commanding 17-3 New England lead.

Brady connected with Amendola, who spun free of Buffalo cornerback Ronald Darby at the New England 45-yard line with nothing but air and green turf between himself and the end zone. But Arthur blew the whistle and the players stopped.

After the officials conferred, the Patriots were awarded the 14 yards Amendola gained on the catch, but no yards after the catch. Another 15 yards were tacked on for a sideline interference penalty called on Ryan. That put the ball on the Buffalo 40, but the Patriots offense stalled.

That left kicker Stephen Gostkowski with a 54-yard attempt, which missed wide right. The Bills tied the game 10-10 on the ensuing possession with a 27-yard LeSean McCoy scoring run.

But the mentally tough Patriots answered, taking a 17-10 lead on a 6-yard James White scoring run with 5:55 remaining in the third.

The Patriots further distanced themselves from the Bills after Buffalo’s Leodis McKelvin fumbled a punt return when he was hit by New England safety Brandon King. Jonathan Freeny recovered for New England and the Patriots turned that into a 35-yard Gostkowski field goal for a 20-10 lead with 47 seconds remaining in the third quarter.

This loss was particularly maddening for Ryan, whose defense had done so much good for so much of the game, disguising blitzes and dropping players into max zone coverage and flummoxing Brady, who completed just 20 of 39 for 277 yards with a touchdown and an interception. Patriots big-play tight end Rob Gronkowski was held to just two catches for 37 yards. The Patriots finished just 4-of-14 on third downs.

A killer sequence for Buffalo came when a 48-yard field goal attempt by Dan Carpenter bounced off the right upright with 46 seconds remaining in the first half.

Six plays later, Brady connected with White with a pass in the right flat and he shook a poor tackle by Buffalo safety Corey Graham at the 10 and scored from 20 yards out for a 10-3 New England lead with 13 seconds remaining in the half.

Ryan was apoplectic with frustration on the sideline, ripping his headset off and slamming it to the ground. It was the opposite scene from the last time the Bills played, when Ryan danced and fist-pumped his way down the MetLife Stadium sideline celebrating the win over his former team, the Jets.

What a difference a week can make in swings of emotions in the NFL. Ten days ago, Ryan was on top of the world, intoxicated with delight over beating his former team in the stadium he coached in and ready to finally defeat Belichick and Brady.

Ten days later, he was done in by his nemesis. Again. The beat goes on.