PHILADELPHIA -- The Phillies outrighted left-hander John Lannan from their 40-man roster Thursday, but he refused his assignment and elected to become a free agent, which wasn't a surprise.

Lannan signed a one-year, $2.5 million contract with the Phillies in the offseason, but he suffered a left knee injury on Aug. 14 that led to his season-ending surgery. He said last month that he hoped to be 100 percent healthy by the beginning of Spring Training, but the Phillies had no plans to tender him a contract as an arbitration-eligible player.

Lannan understood that.

"I pretty much have an idea of what's going to go down," he said. "I'm not an idiot. I'm ready for the challenge, whatever comes up. I just want to make sure [the knee] is right. That's the only thing I can control. The other stuff I can't control."

The Phillies still could re-sign Lannan, with a shot to win a job this spring. The team has holes in its rotation, and a lack of quality depth hurt Philadelphia this season.

Asked if he would be up for competing for a job in camp, Lannan said, "I think it'd be good. I've never come into camp thinking I've locked up a spot. I've always enjoyed the competition. It pushes you a little harder. I'm looking forward to proving to myself, and whoever I sign with or if I stay here, that I can help a team win."