SANTA CLARA — Carlos Rogers is confident he’s still the 49ers’ starter at left cornerback, even if Nnamdi Asomugha’s arrival could prove otherwise.

“There’s going to be competition for cornerback,” Rogers said Tuesday after the start of organized team activities. “(Asomugha) is going to have a big role. They didn’t bring him in to sit on the bench.”

Rogers has started every game since signing as a free agent in 2011. But the 49ers’ pass defense proved vulnerable in the playoffs, culminating with a Super Bowl loss to the Baltimore Ravens.

“I’m told I’m a starter,” Rogers said, referring to Tuesday’s OTA rotation list. “But I go in each and every day thinking someone can take my job.”

Rogers and all four other cornerbacks return from last season’s team, including fellow starter Tarell Brown and the backup trio of Chris Culliver, Perrish Cox and Tramaine Brock.

Joining that corps is Asomugha, who played his first eight seasons with the Raiders before his career stalled the past two years in Philadelphia. Asomugha was among the last players off the field after Tuesday’s session, and he walked off with first-year safety Michael Thomas.

One other noticeable arrival in the 49ers secondary is safety Eric Reid, last month’s first-round draft pick. “The few times we’ve worked out together, he’s real impressive,” Rogers said. “In the classroom, he speaks and talks a lot. I watched him in college and if he plays with the same intensity, we’re not going to miss a beat.”

Another locker-room addition is wide receiver Anquan Boldin, who made what Rogers called a “great catch” against him as the Ravens fended off a 49ers comeback in the Super Bowl. “He hasn’t talked much or bragged,” Rogers said. “We all know he’s got a ring. … Hopefully what he did in Baltimore, he can bring that to this team. He’s going to help this team a lot.”

For more on the 49ers, see Cam Inman’s Hot Read blog at blogs.mercurynews.com/49ers. Follow him on Twitter at twitter.com/CamInman.