Giddens has been waiting to play

J.R. Giddens' spaceship has arrived.

After a season-plus at the end of the Boston bench, Giddens is slated to make a spot start Saturday evening, when the injury-depleted Celtics host the Toronto Raptors at TD Garden.

Ever since a right knee infection sidelined Paul Pierce on Dec. 23, the 6-foot-5, 215-pound Giddens has been tweeting about waiting for his "spaceship," an apparent reference to the Kanye West song of the same name. The track, off the album "College Dropout," chronicles West's inability to progress in his career despite a tireless work ethic, with the refrain, "I wish I could buy me a spaceship and fly past the sky."

Giddens, the Celtics' first-round pick (30th overall) in the 2008 draft, has logged only 21 appearances and 69 total minutes in his brief NBA career. He matched career highs with four points and eight minutes in Wednesday's lopsided loss in Phoenix, but those numbers could both spike Saturday thanks in part to injuries that will prevent three Boston starters -- Rajon Rondo, Paul Pierce and Kevin Garnett
-- from suiting up.

Combined with the absence of Marquis Daniels (left thumb surgery), the Celtics will play with only 11 active bodies, and Glen Davis, who missed Wednesday's game in Phoenix, is still nursing thumb and ankle injuries.

On the eve of a Christmas showdown against Orlando, Giddens tweeted: "Just got out of practice feelin ready if called on, just waitin on my spaceship." But the return of Davis that next day helped shore up the Celtics' bench.

For Giddens, Christmas appears to have come on New Year's Day, as Celtics coach Doc Rivers informed him Friday morning he'd be taking reps with the first team, a solid indication he'll start Saturday, though Rivers would not tip his hand.

Regardless, just being considered for a starting role is a bit overwhelming for Giddens, who played a total of 25 minutes in December.

"I think it's kind of crazy because when I woke up [Friday] morning, it's not what I was expecting to come to the gym and hear," said Giddens. "But, hey, it's great news."

Giddens jokingly prayed that Rivers wouldn't change his mind overnight, but Kendrick Perkins all but confirmed that Giddens is in line for the start during his post-practice chat with the media.

Boston's center stressed that Giddens shouldn't try to do too much, but also said the second-year player needs to be confident.

"I think guys just gotta know their roles out there," said Perkins.

"Play freely, but under control. You can't go out there and play scared. I think [Giddens] has to go out with confidence. You know, just act like you're the man sometimes."

Giddens hasn't been the man for a while. Outside of a stint with the Utah Flash of the NBA Development League last season, he hasn't been a starter since being named Mountain West Conference co-player of the year while averaging 16.3 points and 8.8 rebounds per game his senior season at the University of New Mexico.

A first-round selection of the defending NBA champs, Giddens learned a quick lesson in humility by joining a locker room brimming with talent.

"Being a first-round draft pick and then not getting a chance to play, it's very humbling," said Giddens. "I know I'm so fortunate and I feel so blessed to get it, this has made me appreciate ball a lot more and playing."

Giddens planned to return to the Celtics' practice facility in Waltham on Friday night to get in some extra shots and an additional run. Given his excitement, Giddens wasn't sure he'd be able to sleep Friday.

After all, there's no guarantee that this spaceship will come back after Saturday's game.

"It's a dream come true," said Giddens. "I've been working hard -- working and working -- I have to go out and get it done now. Me getting this chance, it's probably the biggest chance in my NBA career. I don't even know how to describe it in words."

Giddens might also be playing for his future. Earlier this season, the Celtics declined a team option on the third year of his rookie contract, which will make him an unrestricted free agent following the season.

There's always a chance he could return to Boston, and Saturday night could go a long way toward proving why the Celtics need to keep him around.

Giddens planned to call his parents, Charles and Diana, and his two sisters, Breeanna and Portia, to make sure they're in front of the TV Saturday. He's simply hoping to keep his nerves in check.

"I'm sure I'll get a little tingle, a little nervous," said Giddens. "People are mostly nervous the first time they do things, so, yeah, I'll have a couple butterflies."

Giddens is trying to stay grounded, but he did momentarily let news of his potential starting role go to his head.

As the media dispersed around him following Friday's practice, Giddens looked at Celtics PR czar Jeff Twiss and joked, "Twiss, I don't get a soda or anything?" Twiss, who brought Giddens a towel and a T-shirt, didn't bring the second-year guard a beverage like he often does for veteran players chatting with reporters.

Evidently this spaceship doesn't come with in-flight beverage service.

Chris Forsberg is a roving reporter for ESPNBoston.com. Follow him on Twitter.