Tom Brady missed nearly an entire season with torn knee ligaments. Peyton Manning was sidelined all last season by neck surgery and nerve damage that weakened his throwing arm.
That might have been the beginning of the end for lesser quarterbacks.
Not for Brady and Manning, winners of four Super Bowls and six MVP awards between them.
They'll renew their long-running competition on Sunday one week after their outstanding performances in the latest of their many victories. Brady's only team, the New England Patriots, will host Manning's new team, the Denver Broncos. Both are 2-2.
"You're looking at two of the best quarterbacks to play over the last decade," Denver coach John Fox said. "Without a doubt, when their careers are over — hopefully not any time soon for either one of them — they'll be first-ballot Hall of Fame players."
Brady, 35, has said he wants to play into his 40s. Manning, 36, hasn't been as specific but shows no signs of wanting to stop.
Not long ago, though, Manning's future was cloudy. On Sept. 8, 2011 he underwent spinal fusion surgery, the fourth operation on his neck in 19 months.
"I went through the entire rehab process and saw doctors and if the doctor had advised me not to play, then I would not play," Manning said. "I certainly didn't need a year off to re-emphasize how much I enjoy playing."
And he's playing very well after leaving the Indianapolis Colts as a free agent.
In last Sunday's 37-6 win over the Oakland Raiders, Manning completed 30 of 38 passes for 338 yards with three touchdowns and no interceptions. For the season, he's connected on 64.7 percent of his passes for 1,162 yards, eight touchdowns and three interceptions.
"Looks real good, as he always does," Patriots coach Bill Belichick said. "I don't think anybody that we play against is any better in terms of recognizing what the defense is in and where they're weak and vulnerable and how to get to plays that hurt it."
That may be because Belichick doesn't have to play against his own quarterback.
Brady also is coming off his best game of the season. He directed the Patriots to touchdowns on six consecutive second-half possessions in a 52-28 rout of the Buffalo Bills and finished 22 of 36 for 340 yards with a season-high three touchdowns and no interceptions.
He wasn't nearly as impressive early in the 2009 season, his first after undergoing reconstructive surgery on his left knee. He was hurt in the first quarter of the first game of the previous season.
"It's a challenge because you're very rusty. At least I was," Brady said. "We didn't have a great year in '09 when I did come back. It was a very up and down year for us as a team. Peyton has obviously worked very hard and the level that he plays at now, it doesn't look like he missed any time."
The two quarterbacks are friends and Brady said that while he was sidelined in 2008, Manning reached out to him.
"It meant a lot to me," Brady said. "My first start of my career I met Peyton on the field before the game. He was out there warming up. I went over there and he said, 'I'm Peyton Manning'. I was thinking, 'Of course, I know that.'
"It's nice when we're going through some things to bounce an idea off of one another. It's really grown over the years. We've known each other for a long time. We talk about a lot of things. We see each other off the field quite a few times over the years."
It's when Brady and Manning are on the field where fans marvel at — and often compare — their skills.
They first played each other in the third game of 2001, a 44-13 Patriots win over Indianapolis in Brady's first career start. The Colts moved out of the AFC East in 2002, but the teams have met in every season from 2003 to 2011 and three times in the postseason. In head-to-head matchups, Brady has a 6-3 record against Manning in the regular season and 2-1 in the playoffs.
Denver safety Rahim Moore, 13 years younger than Brady, watched him on television before being drafted in the second round last year.
"It's the real deal now," Moore said. "I think him and Peyton are the greatest to ever do it. It shows every week on the field."
But as they usually do before their teams meet, Brady and Manning downplay their individual matchup and emphasize that games are decided by the performances of the entire teams.
"I know it's a boring, boring answer," Manning said, "but it's Broncos vs. the Patriots."
Despite their .500 records, both teams' two losses have been close.
Denver fell to two of the NFL's three unbeaten teams, the Atlanta Falcons and Houston Texans, by six points each. The Patriots lost to the Arizona Cardinals by two points when Stephen Gostkowski missed a 42-yard field goal attempt on the next to last play and to the Baltimore Ravens by one point when Justin Tucker connected on a 27-yard field goal on the final play.
But last Sunday, the Patriots became just the second team in NFL history with a 300-yard passer (Brady), two receivers (Wes Welker and Rob Gronkowski) with at least 100 yards, and two runners (Brandon Bolden and Stevan Ridley) with at least 100 yards.
The Broncos also have a balanced offense. Willis McGahee rushed for 112 yards last Sunday, the second time this season he had more than 100, and Demaryius Thomas and Eric Decker are dangerous receivers.
New England offensive coordinator Josh McDaniels was Denver's head coach in 2009 and 2110 but said he has no special feelings about facing the Broncos.
"It's just the next game," he said.
The Patriots aren't putting much stock in last season's wins over Denver — 41-23 on Dec. 18 that ended a six-game winning streak and 45-10 in the divisional playoffs — with Tim Tebow as the Broncos starting quarterback.
Now, of course, the Broncos have replaced Tebow's scattershot arm with Manning's precision. Brady figures the Patriots will have to score a lot.
"You're not blind to the fact that there's a great player on the other side of the ball that is capable of having a great performance," he said. "You can't think that you're going to score 20 points and think it's good enough or 30 points and think it's good enough."
The Broncos, no doubt, feel the same.
"As long as Tom Brady wakes up and his arm is working," Moore said, "anything can happen."
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