''It wasn't my best day by any stretch of the imagination,'' Rodgers said. ''I gotta play better for us to win. I expect more of myself.''
Rodgers was 17 of 42 for 185 yards, and didn't get much help from his receivers, either. Trailing 16-10 and facing second-and-6 at his own 6, Rodgers found Nelson in stride down the right sideline, but the normally sure-handed receiver dropped the ball with nothing but field in front of him.
''We had all sorts of chances and just didn't make them for whatever reason,'' Nelson said. ''My drop could've won the game for us, so I've gotta make those no matter how easy or hard they are.''
The Packers (10-4) had a five-game win streak snapped and squandered an opportunity to get closer to their sixth consecutive playoff berth.
The Bills (8-6) stayed in the thick of a jumbled AFC playoff hunt. Marcus Thigpen scored on a 75-yard punt return, while Dan Carpenter hit all four field-goal attempts, including three in the second half.
The game wasn't decided until the Packers' final possession, which ended with yet another turnover by Rodgers.
On first-and-10 at his own 10, Rodgers dropped back and had the ball knocked out of his hand by Mario Williams. The ball rolled into the end zone, and lay untouched before being scooped up by Lacy with 1:51 left.
The play was whistled dead at that point, because only Rodgers was allowed to advance the ball with under 2 minutes remaining.
The turnovers were uncharacteristic for a quarterback who had thrown only three interceptions this season - and none since throwing two in a 44-23 loss at New Orleans on Oct. 26.
The Packers were held to 333 yards offense - their lowest total since managing 320 in a 42-10 win over Minnesota on Oct. 2. And the Bills held Green Bay to 10 points on eight first-half possessions. The Packers entered the game having scored six touchdowns and four field goals in each of their previous 10 first-half drives spanning the past two games.
Green Bay travels to play Tampa Bay next weekend, before closing the regular season at home against NFC North rival Detroit.
''Everything's right in front of us. If we win out, we still win the North,'' Rodgers said. ''This is an important time for us to see what kind of chemistry we have on this team.''
The Bills went ahead for good when Carpenter capped their second-half opening drive with a 51-yard field goal.
The game's momentum turned later in the quarter, after Carpenter hit a 35-yard attempt to put Buffalo up 16-10.
Two plays into the Packers' next possession, Rambo sprinted 10 yards from midfield to make a sliding interception of Rodgers' pass intended for Randall Cobb at the Green Bay 45.
His second one came on the Packers next drive when Rodgers' pass intended for Jarrett Boykin over the middle, tipped off the receiver's hands and to Rambo. That set up Carpenter hitting a 48-yard field goal.
Starting right tackle Bryan Bulaga sustained a concussion during Rambo's second interception return. Rambo was playing after backup safety Duke Williams experienced concussion-like symptoms early in the second half.
Thigpen provided a spark after the Bills offense combined for one first down and 12 yards on its first three possessions.
With Buffalo trailing 3-0, Thigpen fielded Tim Masthay's punt at the right hash mark, and then cut across the field to find a hole up the left side.
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