recorded season highs with 111 rushing yards and two touchdowns as the Broncos were in control throughout their 24-16 victory over the slumping Patriots.
The Broncos (6-2) prevailed for the 12th time in their last 14 meetings with the Patriots and moved closer to idle San Diego (6-1) in the AFC West.
"Anytime you can come into someone's home stadium and win, it's a big thing," Portis said. "We snuck out of here with a win and no one said it was going to be easy. We go into the break 6-2 and I think that is a good way to leave for the break."
After beginning defense of their Super Bowl title with three straight wins, the Patriots (3-4) saw their losing streak increase to four games and their self-belief continue to dwindle.
"I think there's some left," Patriots coach Bill Belichick said. "But you know, we have lost four games in a row. It is hard to have confidence."
Griese outplayed former Michigan teammate Brady, completing 18-of-23 passes for 229 yards and a touchdown, with an interception.
Portis, who registered his first 100-yard game in the NFL, reached the end zone for the second time with 2:45 to go in the first half and opened a 21-7 cushion for the Broncos.
"We made three stops in the red zone defense and they scored three touchdowns," Belichick said. "I would like to stop them more than that."
The reigning Super Bowl MVP, Brady threw for just 130 yards on 15-of-29 passing as the Patriots recorded their first four-game losing skid since the opening four contests of the 2000 season.
"It's such a different feeling than we've had, even earlier this year," Brady said. "I think we're extremely frustrated. We go out and play these teams that play awfully well against us and we don't play well enough to win."
New England also became the first defending Super Bowl champion since Denver in 1999 to lose four straight games.
"It's always tough anytime you have a team that has had success like they have," Broncos coach Mike Shanahan said. "I can empathize with them quite a bit because I was in that situation. But they've got too much character. They're going to come back and I believe still have a heck of a season. I wouldn't be surprised to see them in the playoffs."
Another chapter was added to the Griese-versus-Brady saga on Sunday.
Brady was a sophomore in 1996 at the University of Michigan when Griese edged him out for the backup role that ultimately led to a starting job on the 1997 national championship team.
Last October 28, the quarterbacks dueled and Griese led the Broncos to an 11-point victory at Denver.
But Brady bounced back and went on to lead the Patriots to an improbable Super Bowl title and captured game MVP honors.
These teams also are well known to each other, having squared off for the eighth consecutive season - the longest active streak among non-division rivals.
New England was looking for the game-tying touchdown with 3:08 to play when Brady was sacked for the fifth time. But he became incensed when defensive end
was not flagged for apparently pulling him down by the facemask.
"I got him," Pryce said. "I am going to church in the morning. I feel very fortunate."
"I think that is probably one play that could have gone either way and I wish it had gone our way," Brady said. "But I don't think that is why we lost the game. Those are the type of plays when you are losing that you do not get."
Brady then threw an incomplete pass on 3rd-and-22 and New England elected to punt.
On the ensuing drive, Griese connected with rookie
on a 40-yard pass on 3rd-and-8, clinching the victory for Denver.
"We knew they were going to be blitzing and we knew we would have man coverage on the outside," Griese said. "So we were going to take a chance and we had confidence in Ashley that he was going to come down with it."
The Broncos' third down efficiency proved crucial to their success. They converted 8-of-13 in those situations, including all six in the first half.
Griese completed an 11-yard pass to star tight end
on 3rd-and-9 to advance to the New England 15. Three plays later, Portis found the end zone from one yard out and gave the Broncos a 7-0 lead less than five minutes into the game.
"It's disappointing period when you lose. I don't care if its three or four games (in a row)," Patriots receiver
said. "After getting off to such a great start and to have all of this happen, it's disappointing. I'm kind of at a loss for words."
Griese then went to his receivers on Denver's next scoring drive. He hit
for seven yards on 3rd-and-3 and connected with
for 20 yards on 3rd-and-4, moving the Broncos to the New England 8. Sharpe capped the drive with an eight-yard TD catch - his third score of the season - and increased Denver's lead to 14-0 with 14:55 remaining until halftime.
McCaffrey recorded his second 100-yard game of the season, making eight catches for 116 yards.
The Patriots certainly did not help their own cause, converting just 3-of-12 on third down and committing eight penalties for 83 yards.
"The Broncos made more plays than we did and they deserve to win the game," Belichick said. "In the end, we need to do a better job on third down than we did."
Denver also managed the clock beautifully, holding the ball for 35:40. That margin was manufactured in the fourth quarter, when the Broncos ran 12:13 off the clock and the Patriots were powerless to prevent it.