What a difference 12 hours can make.

When the NFL season kicked off in full on Sunday afternoon, it was widely assumed that there were four powerhouses in the AFC. New England was the favorite to repeat as conference champ, but Jacksonville, San Diego and Indianapolis all were given solid odds to dethrone the Pats.

One Tom Brady injury and three upsets later, the AFC could be much more wide open than oddsmakers forecasted.

By now you know that Brady is out for the season after injuring his knee in the Pats' 17-10 win against the Chiefs. The reigning NFL MVP was hit low by Kansas City safety Bernard Pollard, Brady's knee twisted gruesomely and he stayed on the turf.

"Tom doesn't usually stay down," center Dan Koppen said. "So when he stayed down, you could tell."

Matt Cassel, who had thrown just 39 passes in his first three season, came in and was OK in leading New England to the victory, but Cassel hasn't started a game since high school. He was a backup to Carson Palmer and Matt Leinart at Southern Cal.

New England has pride, and no doubt Coach Bill Belichick will use Brady's absence and sudden bandwagon of doubters as a rallying cry. And it's possible that with a weak schedule the Pats could return to the playoffs, but their days of being AFC odds-on favorites are finished.

The Indianapolis Colts figured to be the AFC team to benefit most from Brady's injury. But then Indy went out Sunday night and was dominated by an average Bears team in the debut of the Colts' new stadium.

Peyton Manning hadn't played a down in the preseason, and it showed on Sunday: Manning didn't make the blitzing Bears pay with long passes. He appeared out of sync and wasn't very mobile on that surgically repaired knee. Even his decision-making was questionable.

The Colts had won 21 consecutive games played in September and October, with their last September loss coming Sept. 9, 2004, against the Patriots, which is a big reason they had not been out of first place in the division in 56 regular-season weeks.

"We certainly haven't had one like that in a long time, where we got soundly outplayed," Colts Coach Tony Dungy said. "They outplayed us for four quarters."

The good news is that Manning undoubtedly will get back in rhythm and that defensive end Dwight Freeney looked back in Pro Bowl form after coming off a serious foot injury. The bad news is Indy's schedule: at Minnesota next Sunday followed by a division battle against Jacksonville. It's not impossible that Indianapolis, which hasn't started 0-2 since 1998, could be 0-3 heading into its bye week.

Speaking of Jacksonville, its whole motivation in the offseason was to unseat the Colts atop the AFC South. But perhaps the Jags forgot about fellow AFC South playoff team Tennessee.

The Titans were physically dominant in Sunday's 17-10 win against Jacksonville, holding the Jags to 187 yards offense and 33 yards rushing.

To be fair to the Jags, they lost 13-10 in last season's opener to these same Titans and from there won 11 of their final 15 and scored at least 24 points in each of their final 10 regular-season contests behind the NFL's second-leading rushing attack.

"The only thing this game guarantees is that we won't go undefeated,'' said running back Fred Taylor, who was held to 18 yards. "We'll be fine.''

Still, it has to be concerning in Jacksonville that QB David Garrard was sacked seven times and threw two interceptions - only one less than his regular-season total from last year.

Last but not least among Week 1 AFC disappointments are the Chargers.

San Diego was probably the NFL's hard-luck loser on Sunday as the Panthers' Jake Delhomme threw a 14-yard TD pass as time expired to give Carolina a 26-24 road win. But don't let the fact that the Chargers were leading in the final seconds fool you - they were thoroughly outplayed.

Carolina outgained San Diego in every yardage category, held the ball for a little more than four minutes more overall and led by nine points midway through the fourth quarter despite playing without its best offensive player, suspended receiver Steve Smith.

While Chargers star linebacker Shawne Merriman made it through game unscathed, remember that he is one play from being out for the year with his knee problems. He did appear limited on Sunday, with no sacks and only one solo tackle.

At least the Chargers, who had won 15 of their past 16 games at home, can look on the bright side: Their presumed fellow AFC powers suffered similar or worse fates in Week 1.