He's a dominant presence for us in the middle of our defense. [...] he does take on that role of leadership and take it seriously. The team's outspoken defensive captain recently proclaimed the Broncos will once again beat the Patriots in the playoffs even if it's in Foxborough, where Denver hasn't won since 2006. After coach John Fox admonished him afterward, Knighton didn't back down from the promise he made in the jubilation of Denver's fourth straight divisional title last weekend. After coming up big for the Broncos in their Super Bowl run last season, the loquacious Knighton said he wanted a bigger leadership role this year and his teammates elected him a captain. [...] when you have a top-5 offense and a top-5 defense, and me being one of the main reasons why we have a top defense, shoot, I felt like I had the floor and I could say it. [...] that's why you guys talk to me, but coach Del Rio always told me, since my rookie year, 'You're a grown man. Notes: WR Emmanuel Sanders was sent home during practice Saturday with flu-like symptoms. Aside from the season he missed because of spinal fusion surgery, Manning has never missed a start in his 17-year career.