NFL quarterback great Peyton Manning was preparing to launch the second phase of his career in Denver on Sunday as the man who replaced him in Indianapolis endured a rough welcome to the NFL. Manning\'s official Denver debut -- and his first meaningful contest in 20 months -- was the center of attention on the first full Sunday of action in the NFL\'s 2012 season. The Broncos were hosting a Pittsburgh Steelers squad aiming to avenge the defeat that ended their 2011 season. Then-Broncos quarterback Tim Tebow engineered a 29-23 overtime victory, but despite such moments, the Broncos opted to part ways with Tebow and seize the opportunity to grab Manning, who was let go by the Colts after multiple neck surgeries that caused him to miss the entire 2011 season. \"I know how hard I\'ve worked to get back to this position, how much time I\'ve put in to rehabbing, how much time I continue to put in, how hard I\'ve worked to try to get comfortable in this system,\" said Manning, a four-time NFL Most Valuable Player who led the Colts to a Super Bowl crown in 2007. \"That\'s really all that I know that I can do. I\'m going to play as hard as I possibly can.\" The Colts decided to look to the future and draft collegiate quarterback star Andrew Luck with the top pick in April\'s draft. Thrown in at the deep end, Luck was inconsistent in a 41-21 defeat at the Chicago Bears. Bears quarterback Jay Cutler, who missed the final six games in 2011 with a thumb injury, was intercepted by Jerrell Freeman for a Colts touchdown early in the first quarter but finished with 333 yards (meters) and two touchdowns on 21-of-35 passing. Luck, the first rookie quarterback to start for Indianapolis since Manning in 1998, went 23-for-45 with a touchdown, three interceptions and a fumble. Elsewhere on the first full day of the season, New England Patriots quarterback Tom Brady threw two touchdown passes and Stevan Ridley rushed for a career-high 125 yards with one score as the defending AFC Champion Pats defeated the Tennessee Titans 34-13. Titans quarterback Jake Locker connected on 23-of-32 passes for 229 yards with one touchdown and one interception before leaving his first NFL start in the fourth quarter with an apparent shoulder injury. Washington\'s rookie quarterback Robert Griffin III threw for 320 yards and two touchdowns as the Redskins held off the New Orleans Saints 40-32. Late in the first quarter, Griffin absorbed a hard hit from the Saints\' Malcolm Jenkins before releasing the ball downfield to an open Pierre Garcon, who raced 88 yards for Griffin\'s first NFL touchdown. In other contests, Minnesota edged Jacksonville 26-23 in overtime, Detroit rallied for a 27-23 victory over St. Louis, Atlanta trounced Kansas City 40-24 and Houston defeated Miami 30-10.