BOSTON -- Celtics center Kristaps Porzingis said he's excited about the state of his recovery from offseason surgery on a tendon in his left ankle, and he is optimistic about returning to the court without missing a beat once he is able to play.

"I've been doing a good amount of stuff, doing pretty good," Porzingis said during media day at the team's practice facility Tuesday. "Looking forward to keep making the progress at this rate, and hopefully be back out there with the guys as soon as possible."

Porzingis told ESPN's Ramona Shelburne that his return could come as soon as December, which would be on the early side of the projected 5- to 6-month recovery period after undergoing surgery to repair a torn retinaculum and dislocated posterior tibialis tendon in his left leg in June, shortly after Boston's championship parade.

When Porzingis came to the podium Tuesday, he did so with a big smile on his face and -- more importantly for the Celtics -- no limp in his gait. When asked what he's able to do at this point, not only did Porzingis say that he's running, but also that he went through his first light-contact workout this past weekend.

"Walking obviously with [no limp]," Porzingis said. "I'm running, I'm on the court, shooting normal. ... I'm doing a lot of stuff honestly. I was already kind of with some live contact, doing some stuff and, yeah, it felt really good afterwards.

"I think it's a really good sign that we had from the other day. ... I'm optimistic as always."

The Celtics' practice facility opened up several days earlier than the rest of the NBA because of the team's impending trip to Abu Dhabi to play the Denver Nuggets in a preseason game.

For Porzingis, last year saw him come to Boston in an offseason trade and become an NBA champion for the first time in dramatic fashion. He came back from a calf strain in the first round of the playoffs to play in three games in the NBA Finals, including Game 5 after suffering this rare tendon injury in Game 2.

But while Porzingis arrived in Boston with plenty of questions surrounding his ability to impact winning at the highest level -- all of which he answered with his play last season -- he said he still enters this season wanting to continue to prove himself and to help Boston win a second straight title.

"I'm still extremely hungry," Porzingis said. "I still feel like I have a chip on my shoulder. I want to stay healthy throughout this next playoff run we're going to have, so I still have many things to prove in my own eyes."

In the meantime, Boston will be spending at least the first several weeks of the season playing without Porzingis and using a quartet of players -- veteran Al Horford, who is entering his 18th NBA season, Luke Kornet, Xavier Tillman and Neemias Queta -- to fill in at the center spot.

Horford said Tuesday that the thought of retirement never crossed his mind this summer and that he's put no limits on how long he could continue to play after turning 38 during the NBA Finals in June. He's likely to continue to only play in half of back-to-backs -- like he did last season for Boston -- and is expected to start whenever he does play until Porzingis returns.

Kornet (wrist) and Tillman (kinee), meanwhile, both have successfully recovered from offseason surgeries and are ready for training camp.

"I'm really encouraged by the health of our team," Celtics president of basketball operations Brad Stevens said. "We had Kristaps, obviously he had the surgery that was well documented after the year and seems to be recovering well. He's very optimistic. I don't know that we're interested in putting a timeline on him because the injury is unique. But as far as how he feels and the progress that he's made, I'd say we're very, very pleased with where he is, and maybe a little surprised."