ORCHARD PARK, N.Y. (AP) -- Rookie quarterback EJ Manuel provided the Bills an encouraging glimpse into their future. And defensive end Mario Williams is starting to feel comfortable in Buffalo.
In his second season since signing a $100 million contract, Williams finally began playing up to his high-priced promise by leading the Bills' new-look defense with a franchise-best and career-high 4 1/2 sacks. Manuel, the rookie first-round draft pick, then capped a 24-23 win over the Carolina Panthers by hitting Stevie Johnson for a 2-yard touchdown pass with 2 seconds remaining.
''It boosts our morale,'' Williams said of a team that was still stinging a week after giving up a last-second field goal in a 23-21 season-opening loss to New England. ''It shows that we can believe in each other, take care of our business.''
It was a significant win for a team coming off a near top-to-bottom offseason transition, which included the hiring of rookie coach Doug Marrone.
For Carolina, the outcome proved all too familiar for a team that continues to have difficulty winning close games. Coming off a season-opening 12-7 loss to Seattle, the Panthers dropped to 2-14 in games decided by 7 points or fewer since coach Ron Rivera took over in 2011.
''This isn't about learning any hard lessons,'' Carolina receiver Steve Smith said. ''This is like going to the dentist and getting several teeth pulled without any anesthesia, laughing gas, nothing. It's tough, and it's sickening.''
Here's five things that stood out:
1. ELECTRIC EJ: Shrugging off a pair of second-half turnovers, Manuel completed 6 of 8 passes for 51 yards in marching Buffalo 80 yards in 96 seconds on the decisive drive.
Manuel got help from a pass-interference penalty against linebacker Luke Kuechly that came two plays before Johnson's touchdown. Yet, Manuel showed no signs of fear in throwing over the middle despite the Bills having used up their time outs.
In finishing 27 of 39 for 296 yards passing, Manuel became the NFL's fifth rookie quarterback since 1960 to win a game when trailing in the fourth quarter.
Best of all, the comeback occurred with his father, Eric Sr., celebrating his birthday.
Guess who's getting a game ball as a present?
''I didn't have a gift. My dad's not big on gifts,'' Manuel said. ''But I know he'll definitely want to take this home.''
2. PANTHERS LACK FINISH: Carolina squandered a chance to break the game open by settling for field goals by Graham Gano on three consecutive fourth-quarter drives.
Quarterback Cam Newton threw an incompletion on third-and-goal from the 9, which led to Gano's 27-yard chip shot. Williams was credited with a sack to end the next threat at the Bills 7, before Gano hit a 25-yard field goal.
Newton then marched Carolina 59 yards over 5:35 to set up Gano's 39-yard field goal with 1:38 remaining.
''It killed us. That was the difference in the game,'' said tight end Greg Olsen, who had seven catches for 84 yards, including a 13-yard touchdown. ''We just didn't finish.''
3. SACK ATTACK: Williams' career-day came in his 100th career game. He broke the team record of four sacks set three previous times, once by Cornelius Bennett in 1987, and twice by Bruce Smith (1990 and '94).
The 4 1/2 sacks were the most since San Francisco's Aldon Smith had 5 1/2 against Chicago last Nov. 19. Williams has 6 1/2 sacks this season after he managed 10 1/2 last year.
The Bills finished with six sacks, their most since getting 10 in a 23-0 win over Washington on Oct. 30, 2011.
4. DEPLETED AT DB: Carolina lost both starting safeties to injury after Charles Godfrey (right Achilles tendon) and Quintin Mikell (right ankle) were hurt in the second half.
Starting cornerback Josh Thomas did not return after sustaining a concussion in the first quarter while making a helmet-to-helmet tackle on receiver Robert Woods.
5. C.J. AND STEVIE BOUNCE BACK: A week after being criticized for dropping an easy third-down pass, Johnson bounced back with eight catches for 111 yards, including a touchdown. Running back C.J. Spiller had a solid outing with 16 carries for 103 yards. That included a 46-yard run, which was 5 yards more than he combined for against New England.
It came against a Carolina defense that allowed an average 57 yards rushing in its previous five games.
AP NFL website: www.pro32.ap.org