FLOWERY BRANCH -- Falcons coach Mike Smith was smiling cautiously as training camp opened on Friday.
Smith was happy because all the players lost to injuries in 2009 were back and his top 2010 draft pick, linebacker Sean Weatherspoon, signed just in time for the first practice.
Smith was cautious because he knows it will be difficult to avoid injuries through two-a-day practices in intense heat.
''The biggest thing for us is to stay healthy, especially in the first 10 days of training camp,'' Smith said.
''I think throughout the league as you watch, there's going to be a lot of guys missing time. We want to have our guys on the field.''
Weatherspoon, the first-round pick from Missouri, signed a five-year, $17.5 million contract, including $10.5 million guaranteed. The deal was completed late Thursday.
''My main goal was just to make sure I was out here for practice,'' Weatherspoon said after Friday's first practice. ''You don't want to miss any time out there on the field. It was a big deal to me, getting here.''
Weatherspoon is learning both outside linebacker positions in the Falcons' 4-3 scheme.
''It was fun to get out there and run around and just try to make some plays and knock the rust off a little bit and get back in the swing of things,'' he said.
Weatherspoon is projected to eventually replace 34-year-old Mike Peterson, who is serving as the rookie's mentor.
''He knows everything that's going on out there,'' Weatherspoon said. ''He's played this system for so long. He knows exactly what's going on so I kind of lean on him.''
Weatherspoon was the Falcons' last draft pick to sign.
Smith also celebrated the return of three key players who had season-ending knee injuries in 2009: defensive tackle Peria Jerry, cornerback Brian Williams and receiver Harry Douglas.
Jerry and Williams are possible starters.
Douglas was projected as the team's No. 3 receiver and punt return specialist before he suffered a torn left anterior cruciate ligament in last year's training camp.
''Having (Douglas) coming back, having Brian Williams coming back and Peria, it's only going to help us become a better football team,'' tight end Tony Gonzalez said. ''That's why I'm so excited. That's why this 100-degree weather is just a side note as far as I'm concerned.''
Jerry, a 2009 first-round pick, had a light brace on his left knee in his return from the injury that forced him to miss most of his rookie season.
''I thought Peria looked very good this morning,'' Smith said.
Jerry was held out of team drills in the morning practice. Each of the three were limited to walkthrough drills in the afternoon session. Smith said that pattern could continue for the first two weeks of camp.
''We're going to manage all three of those guys and bring them along,'' Smith said. ''Our philosophy is to make sure they meet certain milestones that are set by our doctor first, our (trainers) and then us as coaches. We're going to be very, very careful on the workload we give those guys, especially through these first two weeks of practice.''
Williams is competing with Brent Grimes and Christopher Owens for a starting job. Dunta Robinson, who signed with Atlanta as a free agent after six years in Houston, is the other starting cornerback.
''I think it's going to be one of the most competitive position battles that we have,'' Smith said.
The Falcons hope Jerry provides an inside push to help the team's outside pass rush.
The Falcons tied for 26th in the NFL with only 28 sacks last season. Kroy Biermann could emerge as John Abraham's new pass-rush complement at defensive end.
Biermann, a third-year player, had five sacks in 2009. Jamaal Anderson, the No. 8 overall pick in 2007, has only 21/2 sacks in 44 career starts, including one-half sack last season. Anderson is working in a new swing role at end and defensive tackle.
Notes: Temperatures soared into the high 90s for the afternoon practice, but Robinson wasn't fazed. ''No, because I played six years in Houston,'' he said. ''This was a good day compared to what I'm used to out in Houston, Texas.'' ... John Parker Wilson of Alabama is the No. 3 quarterback after D.J. Shockley was released in the offseason.