Favre threw three interceptions and lost a fumble, and the Detroit Lions relied on Jason Hanson's five field goals for a 22-14 victory, dealing the Packer playoff hopes a blow.
"I guessed wrong a couple times and I was just off a couple times," Favre said. "That's going to happen in this league. They just made the plays."
Dre' Bly made the most, intercepting two passes to negate scoring opportunities for Green Bay. Bly also forced a Javon Walker fumble, setting up Hanson's go-ahead 49-yard field goal to make the score 16-14 early in the fourth quarter.
The Lions (4-8) surpassed their victory totals from each of the last two seasons and extended their home winning streak to three games.
"I'm glad we had an opportunity to showcase our abilities in front of the world," Bly said
The Packers (6-6) dropped 1 1/2 games behind the Minnesota Vikings, who play at St. Louis on Sunday. Green Bay had won three of its previous four games to get back in the division race.
Green Bay guard Mike Wahle said the Packers "absolutely" have run out of chances to make the playoffs.
"At 6-6, with four games left? You think 8-8 is going to get us in the playoffs?" he asked.
Green Bay Coach Mike Sherman -- and many of his players -- said the Lions played their traditional Thanksgiving Day game with more passion than the Packers.
"This is their football game," Sherman said. "We knew that we were going to have to come out and play 60 emotionally charged minutes of football and we didn't do it. That's disappointing."
In addition to harassing Favre throughout, the Lions held running back Ahman Green to 57 yards rushing. Green came in averaging an NFC-best 120.5 yards and had at least 100 in each of his previous three games.
Green Bay is 21-2 when Green runs for 100 yards.
Favre broke his right thumb Oct. 19 against St. Louis, but on Thursday he tied Forrest Gregg's team record by playing in his 187th consecutive game. It was also Favre's 185th consecutive start, extending his NFL record for a quarterback.
Favre completed 23 of 37 passes for 296 yards with two touchdowns. But in the second half, he threw the three interceptions and had the fumble. Favre's first two interceptions were hard-thrown balls directly at Bly, and the third was an up-for-grabs lob that Doug Evans snatched with about a minute left.
"We were never able to get Detroit on their heels, and that's how you win football games," Favre said.