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KANSAS CITY, Mo. -- Tony Gonzalez boarded the first bus to Arrowhead Stadium on Sunday, eager to arrive as early as possible to start what's likely his final season in the place where it all began.

The Falcons made sure it was a happy return.

Matt Ryan threw for 299 yards and three touchdowns, one of them to the longtime Chiefs tight end late in the third quarter, and Atlanta pulled away with a dynamic second-half scoring outburst for a 40-24 season-opening victory over Kansas City.

"It's been like a homecoming for me," Gonzalez said. "I just want all the fans to know, 'I love you very much and thank you for letting this day be special.' "

They didn't have much choice.

Ryan also ran for a TD, and Julio Jones caught six passes for 108 yards and two scores, both of them enjoying a Chiefs defense missing four starters due to injuries and suspension.

The highlight, though, was Gonzalez, the five-time All-Pro who spent his first 12 seasons in Kansas City. After making his TD grab, the ball squirted loose in the end zone. Ryan tracked it down and pushed it into Gonzalez's hands, and as he'd done so many times, the former college hoops player dunked the ball over the goalpost -- getting mostly boos from a crowd that once cheered him.

"He's such a great part of this organization, you know, probably the greatest tight end to ever play the game," Ryan said. "I think deep down in their hearts, Kansas City fans were happy to see that one more time.

"Maybe not at the time," Ryan quickly added. "Maybe in retrospect."

The Chiefs matched Atlanta most of the first half, trailing 20-17 at the break, but a missed field goal by Ryan Succop early in the third quarter proved to be the turning point.

Atlanta scored 20 unanswered points to put the game away.

Matt Cassel threw for 258 yards and had touchdowns running and throwing, but he also fumbled deep in Kansas City territory to set up a short TD drive, and his two interceptions created short fields that the Falcons turned into field goals by Matt Bryant.

"It's only one game in a long season," Cassel said. "We obviously have to make a lot of corrections and get better as a football team. We've got to play collectively."

There was no controversy surrounding the replacement officials. Both times that referee Mike Shepherd went under the hood for a video review, the original call stood.

Jamaal Charles had 87 yards rushing, and Tony Moeaki had three catches for 37 yards, both providing a bright spot for Kansas City. The pair of them, along with safety Eric Berry, played their first regular-season games since tearing their left ACLs last season.

There were still plenty of injury woes to go along with the suspension of Pro Bowl linebacker Tamba Hali, who missed the game after violating the league's substance-abuse policy.

Starting safety Kendrick Lewis (right shoulder), cornerback Brandon Flowers (right heel) and defensive tackle Anthony Toribio (right ankle) were inactive due to injuries, and that seemed like chum in the water to one of the league's top passing offenses.

"The fact that they weren't there, really no one cares," said Chiefs coach Romeo Crennel, "because all anyone wants to know is did you win or did you lose, and we lost today."

Ryan set the tone with the Falcons' opening series, marching 80 yards behind pinpoint passing before an 8-yard pass to Jones made it 7-0 midway through the first quarter.

The teams swapped field goals before the Chiefs answered with their own TD drive.

Cassel was 4 for 4 on the series, including a 21-yard pass to Dwayne Bowe and a 22-yard TD toss to tight end Kevin Boss, who was signed in the offseason to make precisely the kind of finger-tip grabs down the seam that got him into the end zone Sunday.

The teams kept trading haymakers the rest of the half.

Ryan connected with Roddy White three times on the Falcons' ensuing drive, and a dump-off pass that Jones turned into a 14-yard score gave them the lead again. But the Chiefs had another answer when Cassel weaved his way into the end-zone from 5-yards out late in the second quarter.

Bryant added his second field goal just before half time for Atlanta, but Succop banged his own 40-yard try off the upright early in the second half, shifting the momentum for good.

The Falcons' potent passing offense marched down field, Ryan capping the drive with a 5-yard scramble for a touchdown.

Three plays later, Cassel was blindsided by John Abraham and the ball squirted loose, and Stephen Nicholas pounced on it at the 7. Ryan hit Gonzalez in the back of the end zone on the very next play for a 34-17 lead, effectively putting the game away.

For the Falcons, in the most fitting fashion possible.

"Tony Gonzalez, without a doubt, is going to be a first-ballot Hall of Famer," Atlanta coach Mike Smith said. "We knew it was going to be an emotional week for him and I'm sure he's glad it's over."

Game notes

Atlanta CB Brent Grimes left in the fourth quarter with a calf injury. ... Rookie DT Dontari Poe started in place of Toribio for Kansas City. ... Nicholas had a game-high 12 tackles, recovered a fumble, picked off a pass and had two pass deflections for Atlanta. ... Bryant finished 4 for 4 on FGs for Atlanta.