Then Jacksonville's defense put an end to all that.
Byron Leftwich threw for two touchdowns, Fred Taylor ran for a season-high 132 yards and the Jaguars made a huge stop in the closing minutes to hand the Bengals their first loss of the season, 23-20 on Sunday night.
"This shows how good of a team we have," said Jags receiver Ernest Wilford, who caught an 11-yard touchdown pass in the third quarter.
The Bengals started 4-0 for the first time since 1988 -- the franchise's last Super Bowl season -- and entered the game as one of the last two undefeated teams in the league.
But the Jaguars (3-2) took advantage of good field position early and had two key stops in the fourth quarter that left AFC South rival Indianapolis as the lone unbeaten.
"This was huge," Jags cornerback Rashean Mathis said. "There's a big difference between 3-2 and 2-3. It means a great deal."
Josh Scobee kicked three field goals, including a 51-yarder in the second period and a 53-yarder with 9:45 to play that gave the Jaguars a 10-point lead.
Jacksonville's defense held on from there -- barely -- and kept Palmer from engineering a dramatic comeback.
The Jags ran out the clock from there.
The defense's other key stop came on fourth-and-1 at the Jags 39-yard line with 14:30 remaining. Rudi Johnson ran up the middle, and John Henderson and Marcus Stroud stuffed him for no gain. The Jags then drove 26 yards to set up Scobee's final field goal, which tied his previous career long and the franchise record.
The Bengals used two long passes from Palmer to rookie Chris Henry to cut the lead to 23-20 with 5:16 remaining. Palmer hit Henry down the sideline for a 47-yard gain, then hit the third-round draft pick across the middle two plays later for a 25-yard score.
Aside from the final drive, nearly everything went right for the Bengals late. Very little went right for them early.
Cincinnati fell behind 13-0 before Chad Johnson caught a 14-yard TD pass from Palmer. Cincinnati had a 69-yard punt nullified by penalty, dropped an interception, shanked a punt and had another one blocked -- all in the first half.
The Jaguars had great field possession following the miscues, helping them score a touchdown and a field goal.
"We dug ourselves a hole with field possession in the first half," Bengals coach Marvin Lewis said. "We didn't play very well at the beginning of the game and we were playing up hill."
Leftwich found George Wrighster for a 26-yard score after gaining about 40 yards when Kyle Larson's long punt was brought back because of an illegal touching. Wrighster caught the pass in the flat, hurdled Deltha O'Neal at the 5 and trotted into the end zone.
When Cincinnati put together a decent drive Chad Johnson turned the wrong way on Palmer's deep pass and couldn't get to it. Then Johnson and Palmer argued on the sideline before Lewis had to separate them.
Larson's next punt was blocked, and the Jags had the ball at the Bengals 33. Scobee's 32-yard field goal made it 10-0.
Scobee followed with the 51-yard field goal that made it 13-0.
Palmer and Johnson, having worked things out, hooked up three times on the next drive, including the 14-yarder for a touchdown.
But Johnson complained after the game that Palmer wasn't trying hard enough to get him the ball.
"They didn't get it to me period!" said Johnson, who had five receptions for 52 yards. "They doubled me the whole game. That happens every week. Does that mean that when a team doubles me that I'm through? It's not too hard to get it to (Terrell Owens) or Randy Moss."
Johnson made good on his promise of having something special planned if he scored during Cincinnati's lone appearance in prime time this season. He beat Mathis in the corner of the end zone, then performed CPR on the football. He pretended to give it mouth-to-mouth and three chest compressions.
"We need to win these," Johnson said. I'm not satisfied with 4-1. The Bengals of old might have been OK keeping it close. We're not supposed to be close anymore."
- The Jaguars extended the NFL's longest streak of not scoring at least 30 points to 54 games.
- The Bengals were without three starters: WR T.J. Houshmandzadeh (hand), S Madieu Williams (shoulder) and C Rich Braham (knee).
- Taylor's last 100-yard game came last December, when he tore two knee ligaments against Green Bay.