BOSTON -- After coming up short in his first trip to the NBA Finals two years ago, Boston Celtics star Jayson Tatum said Saturday that he views this return to the league's championship round as a second chance at achieving his ultimate goal as a player.

"It's a lot that myself, and we can learn from that experience being in the Finals, and this time, this go-around is a lot different," Tatum said following Saturday's practice at the team's facility, its second in a row after a break following sweeping the Indiana Pacers in the Eastern Conference finals. "Obviously, we've been there before, we came up short. And a great opportunity to make it to the Finals again. You don't always get a second chance, so really just looking at it as a second chance and trying to simplify things as much as we can.

"It's another series that we gotta win."

Playing through a wrist injury during that series, Tatum averaged 21.5 points but shot just 31.5 percent from 2-point range, including going 6-for-18 from the field in a Game 6 loss here at TD Garden, as the Golden State Warriors went on to celebrate their fourth championship of the Stephen Curry Era on Boston's home floor.

It's taken two years for the Celtics to get a chance to avenge that result, after losing in seven games in the Eastern Conference finals against the Miami Heat -- again seeing their season end here in Boston after Tatum sprained his ankle in the opening moments of that loss, helping prevent Boston from becoming the first team in NBA history to overcome a 3-0 deficit to win a best-of-7 playoff series.

Now, though, Boston finds itself back -- and does so against a familiar foe in Kyrie Irving, who Tatum spent the first two years of his career playing alongside while Irving was with the Celtics. And while the rocky 2018-19 season, and Irving's eventual departure in free agency for the Brooklyn Nets, makes Irving's return here one of the dominant storylines of the Finals, Tatum said the opportunity to play alongside one of the league's superstars early in his career was a tremendous learning opportunity.

"Yeah obviously there were some ups and downs but I think, for me, being a first, second-year player, being around a superstar, essentially, every day and seeing how to navigate that space," Tatum said. "And then obviously on the court, he's one of the most talented guys I've ever seen.

"So it seems like a very long time ago, but I've got a lot of great memories from having (Irving) as a teammate."

Another dominant storyline in this series, of course, is Kristaps Porzingis -- both his health status, after missing the past four weeks, and 10 total playoff games, with a calf strain, and his own reunion with his former team in the Mavericks. As for the health portion of things, Celtics coach Joe Mazzulla said Saturday that Porzingis participated fully in practice, though indicated there would be heavier work days in the ones ahead for the Celtics, as they begin to ramp up for the Finals and maximize their 10 days between series optimally.

When asked about what would go into the decision to either re-insert Porzingis into the starting lineup, or have him come off the bench, Mazzulla said the choice will come down to determining how he can best help the Celtics win games in this series.

"Well I mean, you use him effectively because he's a great player and he's done a lot of great things for us," Mazzulla said. "And then just like any other guy, you go through what gives us the best chance to win, what gives us the best possible chance to win this series, this game, these matchups, these coverages.

"And that kind of just goes down the line for everyone. So when KP's at his best, he's been tremendous for us. We expect that from him and we know he'll give that to us. And as far as everything else, just what goes into winning is the most important thing. What gives us the best chance to win each particular game, each particular possession, and each particular matchup."

For his part, Tatum praised Porzingis for his willingness to fit into what Boston was doing, and make himself an essential part of a 64-win team this season, one who will be a critical part of Boston's hopes of raising an 18th championship banner over the next few weeks with his ability to both protect the rim defensively and stretch the floor -- and operate out of the post, where he struggled in Dallas -- offensively.

"KP essentially did exactly what we needed him to do the entire season," Tatum said. "Whether it was punishing switches or space the five-man, being in the corner, sometimes that might be going possessions without touching the ball. Or it may be when they're switching, we give him the ball five times in a row. Joe talks about everybody's just open-mindedness to whatever we're trying to do.

"We switch things up a lot and we have so many talented, gifted players on the offensive and defensive end. Everybody's just got to be open to trying to different things. And I give KP a lot of credit, especially somebody as talented as he is and obviously as tall as he is. A lot of the big guys may be stuck in their ways doing what makes them comfortable. He got outside his comfort zone a little bit and it made us a better team."