By ARNIE STAPLETON
AP Pro Football Writer
ENGLEWOOD, Colo. (AP) - Peyton Manning's arm strength looks just fine. It's his timing with his new targets that's the biggest question mark facing the four-time MVP as he embarks on his comeback with the Denver Broncos.
Manning doesn't appear bothered by the nerve injury in his neck that led to a series of operations, sapped his power and sidelined the league's most durable active quarterback all of last season.
Ever since he signed with the Broncos on March 20, two weeks after his tearful release from the Indianapolis Colts, Manning has been working hard to refine his rapport and rhythm with his new corps of pass catchers.
He has two old pals from his days in Indianapolis to help him adjust in wide receiver Brandon Stokley and tight end Jacob Tamme.
And he has two of the most promising young receivers in the NFL in third-year pros Eric Decker and Demaryius Thomas, the biggest downfield threat he's ever had.
They lead a deep group of players vying to become the next Reggie Wayne or Marvin Harrison in Manning's aerial show.
"We always talk the opportunities are the greatest right now," Decker said. "We have a future Hall of Famer, a guy who's been to the Super Bowl, an All-Pro, someone who wants to win, too. I think as young receivers, we're hungry, we want to make the most of this opportunity and play our best football this year."
Catching Manning's passes is a thrill for a group of guys who loved Tim Tebow's passion but weren't exactly fans of his erratic passing.
Manning is a perfectionist whom running back Lance Ball called a "player-coach," a description Decker finds appropriate because Manning is that rare breed of superstar who makes everyone around him better.
"It's been great. He's definitely a leader," Decker said. "This guy's going to demand the best out of himself and the best out of his teammates. I think a lot of guys respond to that."
Although he put in hours on local high school football fields playing catch with Stokley and Decker, among others, Manning laments that he only had 17 organized offseason practices to adjust to his new team.
So, he was among the most enthusiastic when training camp got here.
"Now, it's fulltime football," Manning said, the relief evident in his voice.
The Broncos, whose workout Friday was interrupted by a nearby lightning strike, will have 17 practices before they open the preseason at Chicago on Aug. 9.
Manning will be padded up Saturday morning for the first time since playing in his 11th Pro Bowl following the 2010 season.
Before last season, the 36-year-old quarterback started all 277 of the Colts games, including playoffs, during his first 13 years in the league.
He's never faced this much doubt about his durability, or, for that matter, his ability.
Coach John Fox swears he's not among those questioning whether Manning will hold up.
"I worry about all of them but not because of any past injury," Fox said.
Manning said his rehab is a work in progress, and he declines to discuss specifics for competitive reasons, but he said his focus right now really is on developing a rhythm with his receivers.
Decker is the one who's spent the most time on the other end of Manning's passes in Denver, and he said he already sees that work paying off.
"I think every chance you get" to catch Manning's throws "it just makes you better down the road," Decker said.
Manning said it's the Broncos' collection of experienced cover cornerbacks _ Champ Bailey and newcomers Drayton Florence and Tracy Porter _ who will really help Denver's young receiving corps blossom.
Although Andre "Bubba" Caldwell has the speed and shifty moves to push for prime playing time, the Broncos are eager to see what kind of years Decker and Thomas can put together with Manning under center.
Neither has been able to put together a complete season in the NFL. Decker shined for two months last season but faded after Tebow took over at quarterback for Kyle Orton. Thomas missed the first half of the season with a torn Achilles tendon and a shattered thumb but was unstoppable down the stretch.
Decker went down with a knee injury early in the Broncos' wild-card playoff game against Pittsburgh, and Thomas stepped up with four catches for 204 yards, including an 80-yard TD catch from Tebow on the first play of overtime.