By Brian Robb, CBS Boston

BOSTON (CBS) – Jared Sullinger is one of the few young Celtics to have already experienced a taste of the NBA postseason, despite the fact that it came on the sidelines.

The power forward saw his teammates fall short in the first-round against the New York Knicks during his rookie year in 2012-13. That loss was the official swan song of the Big Three era, in part because Sullinger was unable to help the team’s cause after undergoing season-ending back surgery in February 2013.

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A mere two years later, history seemed poised to repeat itself, with the former Ohio Star slated to miss out on postseason action again. Sullinger was ruled out for the season by the team’s medical staff back in February after a fracture was uncovered in his left foot. The Celtics made an exciting postseason push in his absence until, without warning, the 6-foot-9 big man returned ahead of schedule and suited up for the final seven games of the team’s regular season.

Boston closed out the regular season with a 6-1 record with Sullinger back in the fold, and now the talented 23-year-old looms as a potential x-factor in Boston’s first-round series against the Cleveland Cavaliers. In the meantime, he’s trying to prepare his young teammates for what’s to come.

“[Playoffs are a] totally different animal,” Sullinger said at practice on Friday. “Totally different when it comes to college and high school, this is the NBA playoffs. You’re playing against the best. Just gotta prepare and hold yourself as one of the best. Come out with confidence and just play hard.”

Sullinger will continue to come off the bench against Cleveland as he works to regain his conditioning and shooting touch after an initial eight-week absence. Since returning, Sullinger is averaging just five points per game with 31 percent shooting, far below his season averages. However, the former starter remains confident he’ll be able to make an impact against the heavily favored Cavs.

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“I’m feeling a lot better,” Sullinger said. “But for me to be who I want to be, there’s still some time that I’m missing, that I just go out there and help the team. Only time will tell.”

While watching his teammates soar after the All-Star break without him, Sullinger likes the fact that this group has had to scratch and claw their way back into postseason contention and play with urgency down the stretch, despite the fact that no one expected them to do so. That experience and mentality should prove to be valuable as the team faces a daunting challenge against the Cavs.

“We had some playoff-type games. We gave up a lot of big leads early in the season. We’re kind of used to being counted out and I think that’s what makes this team play so well. I think that’s what pushed us into the playoffs — for everybody that said we couldn’t do it. We did it. It’s fuel for the fire,” Sullinger said.

While playing with that underdog mentality, the Celtics must hope Sullinger can show shades of the play that made him one of the team’s top scorers (13.3 points per game) over the first four months of the season. Everything needs to go right for Boston if they want to give Cleveland a series, and Sullinger’s play will be a big part of that equation.

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Brian Robb covers the Celtics for CBS Boston and contributes to NBA.com, among other media outlets. You can follow him on Twitter @CelticsHub.