Roger Federer hasn't returned from surgery looking like a new player, but he says one part of him feels quite different.

The world No. 3 is competing in his first tournament since having arthroscopic knee surgery following the Australian Open.

"It just does feel like a different knee," he said following his opening-round win in Monte Carlo. "I guess I also got to get used to that. It's not painful or anything. It just feels different because I've had a different knee for 34 years. So that's why it's a different feel; but not in a bad way, I must tell you."

Federer, who had the procedure for a torn meniscus, revealed some concerns this week regarding the first surgery of his professional career.

He said he was nervous just before going in and experienced a "down" period "for maybe 12 hours." But the 17-time Grand Slam champion soon saw himself on the road back, adding that "once I got back up walking on the crutches, I felt it would be fine, it's going to be okay."

"The toughest moment was the two hours after waking up," he said. "I couldn't feel my knee, my leg. I could hardly move my toes. It was hurting a little. This is when I was a bit afraid about the future. Suddenly I thought that I needed to really go for it if I wanted to be a professional tennis player. I was wondering ... But then my father came to visit me in the hospital. Mirka [Federer's wife] was there, too.

"The first evening things were already better. We were joking again with my doctor. It was good to see everybody there. The next day, or two days later, I had a meeting with the whole team to talk about our plan: our schedule, how we were going to do the rehabilitation process, what tournament I could start playing again.

"From there, it became a lot more pleasant because I was able to be much more positive mentally. I knew we had a plan. Then I felt improvement every single day. Big improvements. I was surprised how much I could do, how quickly I could do it. I was pretty healthy going into the surgery because I just came off playing best-of-five-set matches.

"Plus, I had December, where I worked out really hard. I think that's also why I was able to bounce back as quick as I did."

Though he said he was pleased to be playing again, Federer admitted that he didn't hanker for the circuit during his time off.

"I was really happy being home,” he said. “I was really happy doing the rehab. I just enjoyed the process of getting better every day. I really thought it was something very different that I've never really had to experience, to this extent, in my career."

His clay-court schedule has yet to be fully determined, with no tournaments scheduled between Monte Carlo and the French Open. However, Federer has indicated that he could play in Madrid and Rome, where he is automatically entered.