Justin Smith has said that he may retire from playing in the NFL before the end of his new contract with the San Francisco 49ers.

The defensive tackle penned a contract extension earlier this week, keeping him with the Super Bowl runners-up until the end of the 2015 season.

The 33-year-old told the San Francisco Chronicle: "I'm playing this [year]. I know that for a fact and then we'll go from there. But I feel good. That's the main thing.

"I won't be a guy that's around for 10 snaps, 20 snaps. It's either I'm going [to play full time], or I'm not going. And when it's time to get my ass out of here, I'm going. I get a ticket like everybody else, so that's what I'm doing."

Smith is currently recovering from surgery to repair a triceps tear.