Terrell Thomas has begun jogging outside a pool this week as he attempts his third comeback from an ACL knee injury.

"Today was a great day," Thomas wrote on his website. "For the first time I started with some movement prep exercises where I focused heavily on the hamstrings and quads on the leg press machine and with body lunges. I completed step-downs to focus on stability. I ran for the first time outside of the pool today where I reached a full jog.

"There was no swelling or discomfort, I did have a little adjustment but as I kept running it felt fine. I worked on some back pedaling as well, which felt good, very fluid motion. I also performed some resistance marches, forward, vertical and backwards. Overall no swelling, pain or discomfort so the first day of running really felt great."

Thomas rehabbed hard last year to come back from a torn ACL suffered in 2011. But he injured his knee again in training camp and needed surgery on his right ACL, which he first tore in college at USC.

The Giants have a $6 million option on Thomas' contract in March, so they are expected to get out of that contract. The Giants signed Thomas to a four-year deal worth up to as much as $28 million in free agency last year, but the option is there to protect themselves in case of another injury. Still, the Giants could re-sign Thomas to a new short-term, low-risk deal.

General manager Jerry Reese suggested last month that the cornerback might be better off moving to safety in his latest comeback.

"The 2013 season starts today for me," Thomas wrote. "I am doing everything possible to return. Today is day 21 of the thirty-day challenge and I hope everyone is still kicking butt. I am definitely seeing the results but most of all it is about mental toughness and being resilient. You can do anything you put your mind to."